SB 



U. S. DEPARTMENT OF AGRICULTURE, 

BDREAU OF ENTOMOLOGY— BULLETIN No. 107. 

L. O. HOWARD. Enlomolosut and Chief of Bureau. 



RESULTS OF THE ARTIFICIAL USE 
THE WHITE-FU?sTtUS DISEASE 
IN KANSAS: 

WITH NOTES ON APPROVED METHODS OF 
FIGHTING CHINCH BUGS. 



OF 



FREDERICK H. BIIAINGS, 

Associatt' Fro/fnnor of Bold ni/ and Bncferiology, 

A XI) 

PRESSLEY. A. GLENN, 

Ass-istant I'rofeasor of Entohioloyy, University of Kansas. 



lasuED Decembeu 21, 1911. 




WASHINGTON: 
GOVERNMENT PRINTING OFFICE, 

1911. 




Qass SDf; - 



U. S. DEPARTMENT OF AGRICULTURE, 

BUREAU OF ENTOMOLOGY— BULLETIN No. 107. *-.- ^ ^ 

L. O. HOWARD, Entomologi.t and Chief of Bureau. >''^ 



RESULTS OF THE ARTIFICIAL USE OF 
THE WHITE-FUNGUS DISEASE 

IN KANSAS: zJt} 

fsn 

WITH NOTES ON APPROVED METHODS OP 
FIGHTING CHINCH BUGS. 



FREDERICK H. BILLINGS, 

Associate Professor of Botany and Bacteriology, 

AND ^^ 

PRESSLEY A.'gLENN, 

Assistant Professor of Entomology, University of Kansas. 



Issued December 21, 1911. 




WASHINGTON: 

GOVERNMENT PRINTING OFFICE. 

1911. 



CvJ^"^ 



<> 



rrp v'v 'iV.9 



LETTER OF TRANSMITTAL 



IT. S. Department op Agriculture, 

Bureau of Entomology, 
Washington^ D. 6'., August 17, 1911. 
Sir : I have the honor to transmit herewith for publication a manu- 
script entitled " Results of the Artificial Use of the "Wliite-Fungus 
Disease in Kansas: With Notes on Approved Methods of Fighting 
Chinch Bugs," by Frederick H. Billings, associate professor of botany 
and bacteriology, and Pressley A. Glenn, assistant professor of ento- 
mology. University of Kansas. 

The chinch-bug situation having become serious in Kansas, pro- 
vision was made by the University of Kansas for the distribution of 
insects infected with the white fungus, S porotrichum glohuliferwm. 

The results of this work are embodied in the following pages, and 
I recommend the publication of this manuscript as Bulletin No. 107 
of this bureau. 

Respectfully, C. L. Marlatt, 

Acting Chief of Bureau. 
Hon. James Wilson, 

Secretary of Agriculture. 



PREFATORY NOTE. 



The chinch-bug situation having become serious in Kansas in 1909, 
provision was made by the University of Kansas for the distribution 
of diseased insects during the season of 1910 in accordance with the 
plan inaugurated by Dr. F. H. Snow during the nineties. The effi- 
cacy of this method of combating chinch bugs, however, has been 
questioned, not only by local investigators who gathered the field data 
for Dr. Snow's later reports, but by observers in other States, where, 
in most instances, the practice of distributing diseased bugs has been 
discontinued. While the demand of Kansas farmers for diseased 
bugs was granted, steps were taken to conduct an investigation of the 
problem of artificial distribution, not from the standpoint of proving 
or disproving Dr. Snow's theories as carried out in the nineties, but 
rather from the standpoint of practicability under present conditions. 

The investigation was placed in charge of the writers, who began 
work in January, 1910, for the purpose of definitely settling the ques- 
tion as to the utility of continuing the work of artificial infection. It 
was felt that the seriousness of the situation to the farmers merited 
a stand that was based on many carefully collected data, so that 
future efforts might be urged along lines shown to be most efficient. 

The writers of this bulletin wish to express their appreciation to 
Chancellor Frank Strong, whose continued interest in the investiga- 
tions made them possible ; to Profs. Stevens and Hunter for helpful 
suggestions; to Prof. Barber for the report of his work on chinch- 
bug inoculation ; to Messrs. Leslie Kenoyer and Otto OpoUo for their 
faithfulness in conducting experiments and taking observations near 
their respective homes ; and to Messrs. E. O. G. Kelly, L. A. Kenoyer, 
and W. C. Bower for collecting weather data. 

Frederick H. Billings. 
Pressley a. Glenn. 

University or Kansas. 
4 



CONTENTS. 



Historical summary of chinch-bug diseases 7 

Results of experiments for 10 years, 1888 to 1897 10 

Outline of work against the chinch bug carried on in Kansas diu-ing 1910 14 

Natural distribution of Sporotrichum in Kansas 16 

Natural presence of Sporotrichum among chinch bugs during hibernation 17 

Natural presence of Sporotrichum in wheat fields and cornfields during the 

spring and summer of 1910 18 

Insects upon which Sporotrichum has been found 20 

Natural distribution of Sporotrichum in the soil and its relation to artificial 

infection 20 

Artificial infection experiments with Sporotrichum in the laboratory 21 

Artificial infection — field experiments 26 

Mr. L. A. Kenoyer's report of hia experiments with Sporotrichum and the 

chinch bug 35 

Remedial measures and conclusions 43 

Bibliography 54 



ILLUSTRATIONS. 



PLATES. 

Page. 
Plate I. Sterile jars filled with soil and chinch bugs, showing diseased bugs 

resulting from a spontaneous outbreak in the jar 16 

II. Fig. 1. — Chinch bug enveloped in growth of the white fungus (Sporo- 
trichum globuliferum) . Figs. 2-7. — Dead chinch bugs, showing 
various degrees of envelopment in the white fungus 16 

III. Various insects killed by the fungus diseases Isaria sp. and Sporotri- 

chum globuliferum 20 

IV. Various insects killed by the chinch-bug iuiigns,Sporotrichum globu- 

liferum 20 

V. Fig. 1. — Patch of corn protected by the oiled-straw barrier. Fig. 

2. — Cornfield showing corn treated with crude oil 52 

TEXT FIGURES. 

Fig. 1. Map of Kansas, showing the number of packages of diseased chinch bugs 
sent out in 1910 by the University of Kansas to the different counties 
in the infested area 15 

2. Map of Kansas, showing all the localities where Sporotrichum was found 

as a natural infection. 19 

3. Diagram illustrating the construction of the dust barrier 48 

4. Diagram illustrating the oiled-ridge type of barrier 50 

6 



RESULTS OF THE ARTIFICIAL USE OF THE WHITE-FUNGUS 
DISEASE IN KANSAS, WITH APPROVED METHODS OF FIGHT- 
ING CHINCH BUGS. 



Historical Summary of Chinch-Bug Diseases. 

Since Dr. Snow, in his First and Sixth Reports of the Experiment 
Station of the University of Kansas, has given a somewhat extensive 
account of the chinch-bug disease prior to 189G, only a brief historical 
summary is deemed necessary in this bulletin. 

Three chinch-bug diseases have engaged the attention of entomolo- 
gists — a bacterial disease and two fungous diseases. Wliat was at 
first supposed to be a bacterial disease was, on further investigation, 
ascertained to be only a normal condition in healthy bugs, so the two 
fungous diseases are the only true ones which have received attention. 

One of the fungous diseases is due to a parasitic fungus, known to 
science as Empusa aphidis^ and popularly known as the gray fungus, 
since it envelops the dead bug in a gray covering; the other is due to 
another parasitic fungus, known to science as SporotHchum globu- 
liferum and commonly known as the white fungus, since it envelops 
the dead bug in a white cottony mass. The latter is of special interest 
to us since it is the one which has been under investigation in Kansas. 

The chinch bug was first noticed in North Carolina in ITSS,*^ In 
the Mississippi Valley it has been known since 1823.'' Since 1840 it 
has been under constant observation in Illinois and other States. It 
proved such a destructive pest from the first that entomologists have 
diligently sought for effective remedies by which its depredations 
could be avoided. 

The first evidence of disease among chinch bugs was noted by Dr. 
Henry Shimer at Mount Carroll, 111., in ISGS.^' According to Dr. 
Shimer's notes, this outbreak was first noticed on low creek-bottom 
land, spreading gradually to the higher localities. The disease 
attacked both the old and the young, and was at its maximum during 
the moist, warm weather that followed the cold rains of June and the 
first part of July of that year. So complete was the destruction of 
the bugs that he wrote on August 8 : 

Scarcely one in a thousand of the vast hosts of young bugs observed in the 
middle of June yet remain alive, but plenty of dead ones may be seen every- 

" Fitch's Noxious Insects of New York, 1865. 
" Dr. Porbes's Insect Life, vol. 1, No. 8, p. 259. 
" See Bibliography, p. 54. 



8 THE WHITE-FUNGUS DISEASE IN KANSAS. 

where lying on the ground, covered with the common mold of decomposing ani- 
mal matter, and nothing else, even when examined by the microscope. Even of 
those that migrated to the cornfields a few weeks ago in such numbers as to 
cover the lower half of the cornstalks, very few are to be found remaining 
alive; but the ground around the base of the corn hills is almost literally cov- 
ered with their moldering, decomposing bodies. This is a matter of so common 
occurrence as to be observed and often spoken of by the farmers. They are 
dead everywhere, not lying on the ground alone, but sticking to the blades and 
stalks of corn in great numbers, in all stages of development. 

Entomologists were slow to accept Dr. Shimer's theory of an 
epidemic disease. AValsh and Riley ridiculed the idea, and Le Baron 
six years later declared that he knew of no predaceous parasitic 
enemies of the chinch bug. Later observations, however, confirmed 
the accuracy of Dr. Shimer's observations. 

Evidence of disease among chinch bugs was not again reported 
until 1882, when Dr. S. A. Forbes, of Illinois,^^ and Prof. Popenoe, of 
Kansas,^^ both reported localities in their respective States in which 
the bugs were dying with a fungus disease which embedded the dead 
bugs in a growth of white mold. 

In August of the same year Dr. Forbes discovered what he thought 
was a bacterial disease due to a bacillus which he found in great num- 
bers in the alimentary canal of dead bugs ; ^^ but after a thorough in- 
vestigation, which extended through several years, he ascertained that 
the presence of the bacillus was a normal condition in the alimentarj^ 
canal of healthful chinch bugs,^^ and the theory of a bacterial disease 
was abandoned. 

The fungus disease noted by Dr. Forbes and Prof. Popenoe was 
what is commonly known as the gray fungus, Empiisa aphidis. 
AVhat fungus was responsible for the disease among the bugs reported 
by Dr. Shinier can not be ascertained. The white fungus had not yet 
been detected. This fungus was first observed by Dr. Forbes in 
Clinton County, 111., July 7, 1887, and again on August 7, 1888.''« ^^ 

For more than a year this fungus affection was not found among chinch bugs, 
although a close watch was kept for it, but August 7, 1888, it was seen at Flora, 
in Clay County, fastening dead bugs to leaves of corn. 

Almost simultaneously it was reported from Minnesota,^^ lowa,^^ 
Ohio, and Kansas.^'^ 

It is worthy of note that no evidence of disease among chinch bugs 
was noted for about 80 years after the chinch bug became known as a 
serious pest, and it was 100 years after its first appearance that the 
white fungus was definitely recognized. It is also all the more re- 
markable in view of the prevalence of the disease over such a wide 
area at this time and during the years following. If these diseases 
were present among the bugs from the first, it seems strange that 
they were not detected earlier, and if they were in the process of in- 
troduction it seems strange that almost simultaneously they should 
be so plentiful in so many different, widely separated localities. It 



HISTORICAL SUMMARY OF DISEASES. 9 

is probable that they were present from the first^ but because of the 
fact that they are so dependent upon the abundance of their host and 
upon favorable weather conditions they are not conspicuous except at 
intervals when conditions are just right. 

In the years immediately following the discovery of the white 
fungus much attention was given to the investigation of chinch-bug 
diseases. 

Dr. Lugger, of Minnesota, was the first to attempt to disseminate 
the disease by the distribution of diseased bugs. In October, 1888, 
he sent diseased bugs to various localities, and the experiment was 
apparently successful, as the bugs in these localities were found to 
be dying with the disease a little later. But the disease spread so 
rapidly that Dr. Lugger was led to suspect very strongly that the 
spores of the disease were already in these localities and that he had 
only reintroduced them, the spread of the disease being due to the 
spores that were already there rather than to the spores which he 
introduced.^^ ^^ 

Dr. Snow's observations and experiments in Kansas began in 1888 
and extended through the season of 1896. In 1888 the chinch bugs 
disappeared from some of the eastern counties of the State during the 
months of May and June, and Dr. Snow expressed the belief that 
they were carried off by an epidemic.^^ Experimenting with the 
gray fungus, Empusa aphidis^ he found that the disease could be 
communicated from diseased bugs to healthy ones by confining 
healthy bugs with the diseased ones. He also sent some diseased bugs 
to farmers and to agricultural experiment stations in Nebraska, Iowa, 
Missouri, Minnesota, Michigan, Indiana, Illinois, and Kentucky. 
The reports received from those who received the diseased bugs were 
very encouraging."® 

In 1890 chinch bugs in Kansas were very scarce, having been very 
generally exterminated in 1889. 

In 1891 the legislature established an experiment station at the 
University of Kansas " to propagate the contagion, or infection, that 
is supposed to be destructive to chinch bugs, and furnish the same to 
farmers free of charge, under the direction of the chancellor, F. H. 
Snow." 

During this period between 40,000 and 50,000 packages of the 
fungus were sent out to farmers, and extensive experiments were 
carried on in the laboratory and some in the field ; the life history of 
the white fungus was worked out, and the best means of propagating 
it in large quantities ascertained. Observers were sent out from the 
station at various times to make observations in the field. The 
reports of these observers in 1891 and 1892 were very favorable, but 
in succeeding years the results of the observations were less favorable 
and brought to light the probability that the fungus was widely 
distributed naturally, since it seemed to be the rule rather than the 



10 THE WHITE-FUNGUS DISEASE IN KANSAS. 

exception that the fungus was working as effectively in fields where 
none had been introduced as in fields where it had been artificially 
distributed. The fungus was found in every locality where the 
inspectors made observations. In commenting on this fact, Dr. Snow 
said : ^^ 

Whether this widely extended natural presence of the Sporotrichum was the 
result of the general introduction of the infection throughout the State, in 1894, 
from the laboratory of this station it would not be possible with certainty either 
to affirm or deny. 

A full account of Dr. Snow's work will be found in his six reports 
of the experiment station of the University of Kansas for the years 
1891, 1892, 1893, 1894, 1895, and 1896. The following is taken from 
his last report : 

RESULTS or EXPERIMENTS FOR 10 YEARS, 1888-1897.^^ 

1. Chinch bugs in any of their stages of development scarcely run the slightest 
risk of death on account of heavy rains, even when these are of long duration. 
They are inconsiderably affected by extremes of heat and cold. 

2. We know of no contagious bacterial disease of the chinch bug. 

3. There are two parasitic, contagious, fungoid diseases that kill chinch bugs, 
namely, Sporoirichum glohuliferum ("white fungus") and Empusa aphidis 
("gray fungus"). 

4. These two diseases show their greatest virulence where the ground is 
damp and shaded from the direct rays of the sun and the air is humid. 

5. We do not know to what extent the spores of these diseases are normally 
present in any given region. When they are present, whether naturally or 
artificially introduced, and the weather conditions are as given above, and the 
bugs are massed together, an outbreak of the diseases will occur. The number 
of chinch bugs killed in any field is approximately proportionate to the number 
of bugs in the field. 

6. Sporotrichum can be artificially communicated to healthy chinch bugs, 
(a) It attacks bugs of all ages, but the older the bug the more easily does ii 
succumb. (&) Bugs of any age that have been weakened from any cause, or 
injured, fall more easy victims to the disease than do those individuals that 
are in perfect condition, (c) The adults of the second brood, which, in the 
ordinary course of events, winter over and lay the eggs for the brood of the 
succeeding spring, are much more successful in resisting the disease than are 
the adults of the first brood, (d) The fungus is not active in winter, and, 
though it be present with the bugs in their winter quarters, they do not die 
of it, even though the winter be as mild and humid as was that of 1895-96. 

The chinch bug seemed to have been almost exterminated in 1896 and there 
has not been any widespread outbreak since until the last two years, and 
hence little opportunity to investigate the practical value of the use of Sporo- 
trichum until this year. Many requests for the fungus were received at the 
university last year, but no provision was made by the university to supply it 

until this year. 

WORK IN OTHER STATES. 

The method of combating chinch bugs by the artificial distribution 
of infection has been extensively used in other States, but in most 
cases the practice has been abandoned. 



HISTORICAL. SUMMARY OF DISEASES. 11 

Dr. Lugger, who first attempted to disseminate the disease by- 
means of distributing diseased bugs in 1888, adopted the plan again 
in 1895. In the First Annual Eeport of the State Entomologist of 
the State Experiment Station of Minnesota for the year 1895, he 
says: 

Judging from the large number of letters, the writers were well pleased with 
the results of spreading spores among chinch bugs. * * * Of course it 
would be folly to claim that the disease was always spread by the introduction 
of such spores, and it is also possible that it would appear simply because the 
climatic conditions were in its favor. Whatever may be the reasons for its 
appearance, so many farmers believe in the effectiveness of introducing spores 
causing the disease that the State can well afford to continue this work. 

However, the practice has been abandoned in Minnesota. Prof. 
F. L. Washburn, State entomologist, in Bulletin No. 77, Agricultural 
Experiment Station, 1902, says: 

We do not know of any profitable means of killing the chinch bugs in the 
grain at present. In this connection we will say that the sending out of dis- 
eased chinch bugs has been abandoned, it having been found that the results 
were not sufficiently practical. 

Dr. S. A. Forbes, who first definitely recognized the white fungus 
in 1887, began an extensive series of experiments with this and also 
the gray fungus, which lasted till 1896. The results of his investi- 
Sfations were not such as to lead him to recommend the use of the 
fungous diseases as a means of combating chinch bugs, although he 
was not ready to declare the method a failure. By isolating bugs 
sent in by farmers, he found that the disease developed among a large 
percentage of them without their being inoculated, and thus was led 
to conclude that the disease was very generally distributed naturally. 
In a series of field experiments he found that the disease was as 
prevalent in fields in which the fungus had not been introduced as 
in the fields in which it had been thoroughly distributed. Accounts 
of these experiments are recorded in the Sixteenth, Seventeenth, 
Eighteenth, Nineteenth, and Twentieth Reports of the State Ento- 
mologists of Illinois, 1888-1896. In the Twentieth Report he says: 

Whether the fungi of contagious diseases can be artificially made use of to 
hasten or intensify the serviceable effect of favorable weather with a frequency 
or to an extent to make this procedure economically worth while, I am not yet 
prepared to say. The methods of distributing these fungi in the fields have 
hitherto been too crude to make their substantial failure conclusive as to the 
whole subject. It now seems quite clear that they can be at the best only 
used as a secondary to other measures, especially the midsummer measures 
described in the third article of this report. If applicable at all, however, they 
can be brought to bear at a point now entirely defenseless, and it seems the 
duty of American economic entomologists to spare no pains to investigate to a 
final and indisputable conclusion which promises so much as a remote possi- 
bility that the chinch bug may be attacked even to occasional advantage after 
it has settled itself in fields of small grain. 



12 THE WHITE-FUNGUS DISEASE IN KANSAS. 

In Nebraska the fimgiis was used extensively in 1893, 1894, and 
1901, but in the outbreaks of 1909 and 1910 the fungus was not recom- 
mended. To those asking for the fungus a circular was sent, which 
says in part: 

It seems that the usefulness of this fungus disease as a method of destroy- 
ing chinch bugs has been greatly overestimated by the farmers, since the ex- 
periments with it show that it spreads only when the weather conditions are 
just right — that is, when the temperature is somewhere between 70° and 80° F., 
and the air is very humid, and when bugs are massed in sufficient numbers 
that they come in contact with each other. When such conditions exist, the 
disease spreads rapidly and destroys the bugs very effectively, but under other 
conditions, especially in dry weather, the disease is quite ineffective. It is be- 
cause of this extreme imreliability of the chinch-bug fungus disease, and its 
failure to spread when most sorely needed, that we have come to regard it as 
more of a detriment than a benefit in many cases, since it causes the farmer to 
place confidence in an unsafe measure to the neglect of more practical, though 
also more laborious, means of control. 

The fungus was also used in Missouri, but has been discarded. 
Prof. J. M. Stedman" says: 

A great many people send in to this office in the spring of the year for the 
chinch-bug disease, with the idea of scattering this disease about the fields of 
wheat and killing the chinch bugs infesting them. It is a fact that under cer- 
tain climatic conditions this chinch-bug disease * * * -^^n jjj^j ^ great 
number of chinch bugs. But from seven years' experience with this disease in 
the wheat fields throughout the State of Missouri I am firmly convinced that 
the artificial use of this disease by the far)ners of Missouri does very little, if 
any, good. * * * in the first place the chinch-bug disease is a natural one, 
found in nature, and is not an artificial one. * * * 

* * * If the chinch bugs are in large numbers and the weather is hot and 
very moist, these spores will germinate on the bugs, and the fungus plant will 
kill them in great numbers. But if the weather is hot and dry, or too cool, 
although it may be moist enough, then the spores will not germinate, and no 
agriculturist has the power to bring about the proper conditions in his wheat or 
cornfield that will enable them to germinate. * * * 

* * * I wish to say that it is very doubtful whether there is a wheat field 
or a cornfield in Missouri that does not naturally contain spores of this disease. 
I have been impressed with this fact evei-y summer, because almost invariably, 
when the person applying for the chinch-bug disease sends to this office living 
chinch bugs that have been placed, as they should be, in a tin box containing 
no dirt, but some green vegetable matter, as for instance, pieces of gi'een corn, 
wheat, or grass, and the box closed up as it should be, perfectly tight, thereby 
generating moisture in the box from these green vegetables, that by the time 
these bugs reach me the box contains more diseased fungus-covered bugs than 
we return ; thus showing that the spores were already there in his field. 
* * * Knowing these facts, I can do no other than to conscientiously advise 
the farmers of Missouri not to trouble themselves with obtaining and scattering 
this disease about their fields, but to rely entirely, as they will ultimately have 
to do, upon nature to bring about the proper climatic conditions for the de- 
velopment of this disease in their fields. 

" Bulletin No. 51, Agr. Exp. Sta., University of Missouri, July, 1902. 



HISTORICAL SUMMARY OF DISEASES. 13 

Prof. F. M. Webster was one of the first to interest himself in the 
investigation of the fungus. As a special agent of the United States 
Department of Agriculture, located at La Fayette, Ind., he conducted 
some experiments which showed that moisture and a large number of 
bugs are essential factors in the successful propagation of the dis- 
ease.'® Later, as State entomologist of Ohio (now connected with 
the U. S. Bureau of Entomology), he experimented with the fungus 
in Ohio in 1895 and 1896. As 1895 was a dry season the fimgus 
proved ineffective ; but in 1896 the weather conditions were favorable, 
and Prof. Webster states : "^ »' 

I have always held to the opinion that the parasitic fungus Sporotrichum 
globuliferum could only be used in a manner to effect relief to the farmers dur- 
ing wet seasons and where there was a superabundance of host insects * * *. 
This year (1896) I can say with all conditions favorable, Sporotrichum globuli- 
ferum has done all that Dr. Snow or any other entomologist claims for it, 
but under conditions as adverse as these have been favorable the results will 
prove quite the reverse. 

It would seem that Prof. Webster's subsequent observations have 
not materially changed his views ; for he states in November, 1909 : * 

As the fungus has many other host insects, it is probably present to a greater 
or less degree throughout the country every year. There is no doubt that 
during wet weather considerable benefit may be derived from the artificial 
cultivation and application of this fungus, but its efliciency is very dependent 
upon this meteorological condition, and, as has already been shown, chinch bugs 
develop in greater abundance in dry seasons. It will thus be seen that only 
during unusual seasons, that is to say, seasons that have been very dry while 
the chinch bugs were hatching from the egg, but wet afterwards, can satis- 
factory results be expected from this measure. 

Thus it appears that the use of the fungus has not come into gen- 
eral use as a means of combating the chinch bug. Its use has been 
abandoned in nearly every State that has given it a good trial. Only 
three States sent out fungus during that season — Oklahoma, Ohio, 
and Kansas. Dr. Gossard, of Ohio, questions very seriously the 
wisdom of sending out the fungus and our investigations in Kansas 
this season, as the report shows, have made it certain that in Kansas 
at least the artificial distribution of the fungus is unnecessary. Its 
failure to come into general use may be ascribed to the following 
reasons : 

1. The disease proves effective only during unusually wet seasons 
and when the bugs are very plentiful. 

2. The disease is quite generally present in the field naturally. 

3. Dependence on the fungus leads farmers to neglect other more 
practical means of control. 

« Circular No. 113, Bur. Ent., U. S. Dept. Agr., 1909. 



14 THE WHITE-FUNGUS DISEASE IN KANSAS. 

Outline of Work against the Chinch Bug Carried on in Kansas 

DURING 1910. 

Owing to the presence of chinch bugs in destructive numbers over 
a considerable portion of the State in 1909, many requests were re- 
ceived for diseased bugs. The demands l3ecame so insistent that the 
regents of the University of Kansas made provisions for supplying 
the fungus to all applicants during the season of 1910. Following 
the methods used by the late Dr. Snow, a package of diseased bugs, 
accompanied by the necessary literature, was mailed to each appli- 
cant. The mailing list was primarily for residents of Kansas, but 
a number of farmers in Oklahoma were supplied with the fungus. 

The literature consisted j^rincipally of a four-page folder, which 
contained, besides information for the use of the fungus, other infor- 
mation which was designed to enable the farmers to make intelligent 
observations in their own fields and to avail themselves of other 
methods of fighting chinch bugs. 

It was understood that many authorities do not advocate the arti- 
ficial use of Sporotrichum ; still, in the absence of conclusive evidence 
to prove its impracticability, the recommendations of Dr. Snow in 
his last report were followed, with the hope that in the face of a 
threatened chinch-bug epidemic some good might result. 

At the same time, however, provision was made for an investiga- 
tion in order to determine definitely whether or not artificial infec- 
tion accomplishes results sufficient to justify the labor and expense 
involved. 

Work began early in 1910, some months before any infection was 
sent out. It was necessary to determine early which portions of the 
State were suited for carrying on experiments, judging from the 
number of bugs, and the extent of the distribution of the fungus 
naturally in the soil. Data as to the distribution of the fungus were 
regarded as more nearly conclusive if obtained before artificial dis- 
tribution began. 

No Sporotrichum had been distributed in Kansas since Dr. Snow 
distributed it from 1891 to 1896. Dr. Snow's reports show that the 
fungus was very generally present in the fields in 1895 and 1896, 
and on that account results derived from its artificial distribution 
were of doubtful benefit. This was thought to be a very favorable 
time for determining if the fungus had meanwhile maintained itself 
in the fields. Whether or not the fungus found in the soil at that 
time was the result of that sown by Dr. Snow years ago is, however, 
not pertinent to the problem, since the problem concerns itself with a 
plan of action for the present and future. 



OUTLINE OF WORK AGAINST CHINCH BUG. 



15 



In comparing the First Annual Keport of Dr. Snow for 1891 with 
the last one for 1896, we find statements which would lead us to 
believe that the artificial distribution of the disease had at least the 







is y 



effect of increasing the amount of Sporotrichum, even if we doubted 
its first introduction into Kansas in the nineties. 
In the report of 1891 we read : 

It must be remembered that tbese contagious diseases of the chinch bug are 
naturally present in certain portions of the Mississippi basin during every 
10944°— Bull. 107—11 2 



16 THE WHITE-FUNGUS DISEASE IN KANSAS. 

year, and become epidemic over large portions of this area in occasional years. 
The object of my experiments has been to artifically introduce the disease at 
times when they are not naturally raging in the fields. It was found in 1891 
that there was no evidence of a natural existence of the three diseases in any 
part of the State of Kansas. This statement is abundantly substantiated by 
the detailed report of my field agent. Mr. Hickey, and by the reports of many 
farmers. 

In his final report Dr. Snow makes this comment : 

While no such general epidemic of Siwrotrichum was noted in this year 
(1896) as occurred in 1895, yet the disease seemed present in those parts 
of the State visited, wherever favorable conditions existed, and in the fields, 
whether artificially infected or not. 

It was therefore doubtless true that in the later years of Dr. 
Snow's campaign many spontaneous outbreaks occurred, and that 
condition's were perhaps not widely diflPerent from what they are 
to-day. Owing to a lack of scientific data, however, there is room 
for doubt as to the absence of Sporotrichiun from Kansas soil prior 
to the recorded observations in 1891. 

The investigations summarized in this paper had chiefly to do 
with the following problems: 

1. Extent to which the white fungus disease of the chinch bug is 
naturally present in Kansas soil. 

2. Practicability of artificial infection of fields in which the fungus 
disease is found to be naturally present. 

3. Practicability of artificial infection of fields in which the fungus 
disease is shown to be scarce, or at least ineffective. 

4. Experiments with barriers and insecticides. 

Among other matters considered were (1) laboratory methods of 
propagating Sporotrichum ; (2) artificial inoculation of chinch bugs 
with spores. 

Natural Distribution of Sporotrichum in Kansas. 

In any investigation to determine the efficacy of artificial infec- 
tion of a field with a. parasitic fungus, the presence or absence of 
the fungus is one of the first points to be determined. If its ab- 
sence be proved, a widespread persistent application of the infec- 
tion might result in a considerable mortality of bugs, provided, of 
course, they are numerous enough to spread the contagion among 
themselves ; but if the presence of the fungus is shown to be general, 
the problem resolves itself into that of attempting to improve natural 
conditions by artificial ones. Theoreticallj^, at least, such a thing 
would be possible, but its practicability must be determined by actual 
experiment under a variety of conditions. It would have to be shown 
that enough bugs, beyond what naturally would have died, succumbed 
to the artificially sown fungus to make the effort worth while. 



Bui. 1 07, Bureau of Entomology, U. S. Dept. of Agriculture. 



Plate I. 




Sterile Jars Filled with Soil and Chinch Bugs, Showing Diseased Bugs 
Resulting from a Spontaneous Outbreak in the Jar. (Original.) 

The white spots in the jars are fungus-covered bugs. 



Bui. 107, Bureau of Entomology, U. S. Dept. of Agriculture. 



Plate II. 




Fig. 1.— Chinch Bug Enveloped in Growth of the White Fungus 
Sporotrichum globuliferum. From Photomicrograph Enlarged 
X 22. (Original.) 

Figs. 2-7.— Dead Chinch Bugs, Showing Various Degrees of En- 
velopment in the White Fungus. From Photographs Enlarged 
X 7. (Original.) 



NATURAL PRESENCE DURING HIBERNATION. 17 

A spontaneous outbreak of the fungus in a field into which no 
fungus had been introduced would imply its natural presence there; 
and, conversely, its natural presence there would imply that a 
spontaneous outbreak would be possible, if given proper conditions. 
Hence it was determined to visit representative counties distributed 
through the infested area, and by examination of fields taken at 
random ascertain to what extent Sporotrichum is present in Kansas 
soil. 

Natural Presence of Sporotrichum among Chinch Bugs during 

Hibernation. 

As conditions for the development of the chinch-bug disease were 
not favorable while the bugs were in hibernation, partly because of 
the cold or cool dry weather that prevailed and partly because of the 
resistant state of the insects, it was necessary to collect them and 
bring them into warm, moist surroundings, where^ with increased 
activity, without food, their vitality would be diminished sufficiently 
for them to succumb to the attack of the disease. 

The type of collecting jar adopted was an 8-ounce square bottle 
with wide mouth and metal screw top lined with cork. This was 
light in weight and packed well in a carrying case. Before taking a 
lot of bottles from the laboratory they were thoroughly sterilized in 
an autoclave. The tops were left loose during sterilization and then 
screwed down tightly upon removal, while hot, from the sterilizer. 

After placing a number of bugs and a small quantity of earth in 
a bottle, by the use of sterilized tools, the lid was screwed down 
tightly and not removed until the bugs were dead, unless the soil in 
the bottle was too dry, in which case a little water was added, either 
from a near-by source in the field or else in the laboratory. If in the 
laboratory, precautions were taken against exposing the contents of 
the bottles to contamination. The tops were loosened and lifted on 
one side only, and then just enough to permit the entrance of a sterile 
pipette, filled with sterile water. By working expeditiously no more 
danger of contamination from the air resulted than in making trans- 
fers from one culture medium to another. 

The favorite places for hibernation on the part of the chinch bugs, 
apparently, were the stools of the prairie grass, Androfogon sco- 
parius. The grass was uprooted and some of the bugs placed in 
bottles by the use of sterile lifters. Several bottles of bugs, together 
with a portion of the surrounding earth, were collected in at least 
one locality in each county visited. 

It was desired to ascertain if a spontaneous outbreak of the fungus 
could be obtained among the incarcerated bugs. Since, under the 
natural conditions to which the bugs were subjected in the bottles, 



18 THE WHITE-FUNGUS DISEASE IN KANSAS. 

there was a possibility that the proper conditions might not be 
secured in some of them for the fungus to develop, the uncer- 
tainty was eliminated by having a number of bottles from each 
locality. Sporotrichum appeared in most of the bottles (see PL I), 
though its occurrence in but one of a series was sufficient to establish 
the certainty of its presence in the locality from which the collection 
had come. In some of the bottles no Sporotrichum developed. This 
was generally due to an excess of moisture which caused bugs to 
die before the Sporotrichum had time to make its presence manifest. 

The chinch bugs in the bottles generally showed remarkable 
powers of endurance, as they were without food yet in warm sur- 
roundings. Some were found still crawling more than two months 
after collection and long after observations were taken. Some con- 
tinued to live for this length of time with the Sporotrichum present 
and projecting conspicuously from dead bugs (see PL II) over which 
they frequently crawled. 

Thirty-two counties in the infested area of Kansas were definitely 
shown to contain the white-fungus disease among the chinch bugs 
before egress from their winter quarters, during the latter part of 
March. 

The first package of diseased bugs was sent out April 7 by the Kan- 
sas State Agricultural College at Manhattan. Five days later the 
University began its distribution of diseased bugs. It is therefore 
evident that Sporotrichum was present naturally in the localities 
examined and only needed the proper climatic conditions to break 
out spontaneously in the fields. 

Natural Presence or Sporotrichum in Wheat Fields and Corn- 
fields DURING THE SpRING AND SuMMER OF 1910. 

Spontaneous outbreaks. — The chinch bugs left their winter quar- 
ters the last week in March, but owing to the dryness and coolness of 
April, no diseased bugs were found in the fields until late in the 
month. In the meantime the collecting of bugs and testing for the 
presence of the fungus continued. Later, when fungus-covered bugs 
were present in the fields, they were considered as direct evidence of 
its natural distribution, provided artificial distribution had not been 
resorted to. 

Observations on the jDresence of Sporotrichum among chinch bugs 
in grain fields occupied the months of April, May, and June. During 
this time 27 additional counties were shown to contain the fungus. 
Summing up the work on the natural distribution of the fungus 
disease, it was found that 59 counties, which include most of the 
infested area of Kansas, showed evidence of its presence. Six coun- 
ties, four of which were on the western edge of chinch-bug distribu- 



NATUEAL PRESENCE IN" FIELDS. 



19 



tion, where excessive drought or else scarcity of bugs constituted the 
conditions met with, failed to show presence of Sporotrichum. Two 
counties, on the northeastern border, because of great scarcity of bugs, 
also failed to show signs of fungus. A few counties situated amono- 




others in which Sporotrichum was observed probably contained it, 
but, as they were not visited, no direct evidence was obtained. 
Granting its absence in such localities in 1910, however, it would be 
but a short time, owing to migration of the chinch bugs, before 



20 THE WHITE-FUNGUS DISEASE IN KANSAS. 

spores from the adjacent counties would be carried over into every 
field where they might alight. 

As will later be shown, Sporotrichum is not dependent on chinch 
bugs for hosts, but may live on other insects. There is hardly any 
question as to the presence of the fungus in the soil generally. 

Maintenance of Sporotrichum in the soil. — From the ease with 
which Sporotrichum is cultivated in the laboratory at room tem- 
perature with dead organic substances as culture media, it is possible 
that it projjagates itself, at times, saprophytically in the soil. It is 
not dependent, however, either on dead organic matter or on living 
chinch bugs, but may live as a parasite on other insects, some of 
which are present in Kansas as permanent fauna. Various writers 
from widely separated localities have reported Sporotrichum on 
insects other than chinch bugs. While making no attempt to search 
for the fungus on other than chinch bugs, the writers noticed insects 
from time to time displaying the characteristic Sporotrichum 
growth. A list of them is given below. 

Insects upon which Sporotrichum has been Found. 

Three common snout beetles, Trichoharis texana, G onotrachelus 
erinaceus^ and Anthonomus fulvus (PI. Ill, figs. 1, 2, and 3) ; a com- 
mon flea-beetle, Disonycha triangularis (PL III, fig. 4;) a very com- 
mon lady-beetle, Hippodamia convergens (PL III, fig. 5) ; a minute 
beetle of the genus Olihrus (PL III, fig. 6) ; and three true bugs 
belonging to the same order (Hemiptera) as the chinch bug, one 
a rather rare insect, belonging to the family Phymatidae, the species un- 
determined, and the other two common forms, Microtoma carhonaria 
and Coriscus ferus (PL IV, figs. 1, 2, and 3), and two unidentified 
larvae (PL IV, figs. 5 and 6), and many common pentatomids. 

Natural Distribution of Sporotrichum in the Soil and its Kela- 
TiON TO Artificial Infection. 

The general distribution of Sporotrichum naturally in the soil 
might affect the artificial use of the fungus in one of two ways — ^by 
rendering it unnecessary, or by making it more effective. In the 
former instance a spontaneous outbreak would occur, which, if con- 
ditions were right, would be of such magnitude that, whatever man 
might do in the way of artificially distributing fungus spores, noth- 
ing appreciable would be added to the results ; or, given unfavorable 
conditions with a slight spontaneous outbreak, or none at all, artificial 
infection would not measurably spread the disease. In the second 
instance when there is already a spontaneous outbreak of considerable 
size, artificial infection might increase this to an epidemic that 
would end in a high percentage of mortality among the bugs. Other 



Bui. 107, Bureau of Entomology, U. S. Dept. of Agriculture. 



Plate III. 




Various Insects Killed by Fungus Diseases. No. 2 is Isaria sp., the 

OTHERS SPOROTRICHUM. (ORIGINAL.) 



Fig. l.— Tiichobaris texana. 
Fig. 2. — Conotrachelus erinaceus. 
Fig. 3. — Anthnnomus fulvus. 



Pig. 4. — Disonijcha triangularis. 
Fig. 5. — Hippodamia convergens. 
Fig. 6.—Olibnos sp. 



Bui, 107, Bureau of Entomology, U. S. Dept. of Agriculture. 



Plate IV. 




Various Insects Killed by the Chinch-Bug fungus, Sporotrichum 
globuliferum. (original.) 



Fig. 1.- 
Fig. 2.- 



-MacrDcrpliahis sp. 
-Micrutotiia atrata. 
Figs. 



and 0.- 



Fig. 2.—Co)-iscusferiis. 
Fig. 4. — C'urisniK ferun, iivniph. 
-Unidentified larv?e. 



INFECTION EXPERIMENTS IN LABORATORY. 21 

fields not artifically treated would then show merely a spontaneous 
outbreak with a lower percentage of mortality. The settlement of 
these problems was merely a matter of experiment under conditions 
that would cover possibilities mentioned above. As soon as spring 
opened and weather permitted, field investigations began; the pur- 
pose being to ascertain whether artificial treatment of a field infested 
by chinch bugs would prove profitable. One phase of the matter 
as described earlier in this paper had already been settled; the 
Sporotrichum disease was widespread naturally over the infested sec- 
tion of the State. It remained to be shown, first, whether sowing 
fungus spores in an already infested field would increase the epidemic, 
and, second, in a field showing but little evidence of Sporotrichum 
whether such a treatment would start an epidemic, otherwise im- 
probable. 

Artificial. Infection Experiments with Sporotrichum in the 

Laboratory. 

Preparatory to the field work it was found necessary to experiment 
with the fungus in the laboratory in order to determine the best 
method of propagation and the effect of the artificially grown cultures 
on chinch bugs. Quite definite results had already been obtained 
by Stevens, Barber, and Forbes, and advantage was taken of their 
conclusions, but at the same time it was thought best to experiment 
anew and adopt the methods best adapted to the experiments in hand. 

Sporotrichum was first isolated from transfers made into nutrient 
agar from a chinch bug dead of the disease. Once obtained pure, 
there was no difficulty in propagating it on artificial media. 

For field infection large quantities were needed, so that infection 
boxes which were designated for infecting bugs for distribution 
to farmers proved inadequate. The 10 c. m. petri dish used in 
bacteriological investigation was selected as the vessel in which to 
place the nutrient medium for growing the Sporotrichum. The fun- 
gus will grow on ordinary beef broth agar, but this was not found so 
useful as a combination of potato extract and corn meal. 

Virulence of artificial cultures. — It was realized early in the in- 
vestigation that the value of any work along lines of field infection 
depended upon a knowledge of the virulence of artificial cultures, 
since these were to be employed to a large extent. It was found that 
so much more fungus could be produced artificially with such cer- 
tainty that diseased bugs, while used, were not depended on for the 
major part of the work. To test the virulence of the fungus, experi- 
ments were conducted at various times by artificially infecting 
chinch bugs with culture fungus (that grown on the potato-cornmeal 
medium) and then comparing results with others not so infected or 
infected by the use of diseased bugs. 



22 THE WHITE-FUNGUS DISEASE IN KANSAS. 

Experiment 1. — This experiment was started April 29, the bugs 
being collected at Colony, a locality which showed an extraordinarily 
small amount of Sporotrichum in the soil when compared with other 
localities (except Garnett, in the same county). By selecting bugs 
from Colony it was hoped to avoid, as far as possible, the presence of 
spores on the bugs or in the soil before the experiment began. The 
insects were collected in five sterile bottles, with an approximately 
equal quantity in each. One bottle was infected with spores from an 
artificially grown culture. The other four bottles were not opened 
after they were sealed in the field. By May 13 three diseased bugs 
were noted in the infected bottle. Four days later all the bugs in 
the bottle were dead and about half of them were covered with a 
visible and typical growth of Sporotrichum. The bugs were dead 
in the four check bottles, but no fungus developed. 

Experiment 2. — This experiment was designed to reach the same 
as the previous one, but by a different method. It began May 7. 
Six screw-capped bottles, each containing 100 grams of earth, were 
sterilized in an autoclave. Bugs direct from the field and not arti- 
ficially infected were placed in three of them. To the other three 
bottles were added bugs, in approximately equal numbers, which had 
been allowed to crawl for two hours over a moist Sporotrichum 
culture. 

Final observations were taken 10 days later. In the uninfected 
bottles no fungus developed. Two of the other three contained two 
and eight diseased bugs, respectively. Xo fungus appeared on the 
third. The short period of 10 days duration to an extent eliminated 
deaths by Sporotrichum resulting from extreme weakness due to pro- 
longed incarceration and starvation. 

Experiment 3. — ^This experiment was designed to compare the rela- 
tive effectiveness of fungus grown on a culture medium and that 
arising naturally on chinch bugs. Thirty sorew-capped bottles were 
prepared with 100 grams of soil in each bottle, then the whole was 
sterilized in the autoclave. About 18 chinch bugs were placed in 
each bottle. A sterile pair of forceps was used to transfer the bugs, 
and unsterilized field earth was avoided as far as possible. Bottles 
1 to 10 were checks. No. 10 having no infected material added. Bot- 
tle 11 contained bugs which had been shaken up in a small box with 
three fungus-covered bugs which were finally added to the bottle 
before it was sealed. Bottle 12 was prepared in the same manner. 
Bottles 13-17 contained bugs that had been shaken up with a lot of 
crushed diseased bugs. Bottles 18-20 contained bugs that had been 
shaken up with soil which had previously been made infectious by 
rubbing up diseased bugs in it. Bottles 21-30 contained bugs that 
had been allowed to crawl over a mass of Sporotrichum grown on 
culture medium. 



INFECTION" EXPERIMENTS IN LABOEATOEY. 



23 



All bugs were collected at Cherryvale, a locality that showed an 
abundance of Sporotrichnm in the soil; hence the positive results in 
the check bottles. The experiment began May 7, and by May 24 all 
the bugs iii all the bottles were dead. 

The results are tabulated below : 

BOTTLES 1 TO 10. 





1 


2 


3 


4 


5 


6 


7 


8 


9 


10 






Date. 


Number of diseased bugs. 


^ay 10 






















^ay 13 


1 

1 
1 




















j^ay 16 






1 
1 














May 24" ! 


1 


2 


1 




1 


2 




1 






Total number of diseased bugs, 13. 

BOTTLES 11 TO 


20. 


Bottle No 


11 


12 


13 


14 


15 


16 


17 


18 


19 


20 






Dat«. 


Number of diseased bugs. 




2 
1 
1 

1 










1 

1 
1 


3 
1 


"2 


2 


1 


May 13 


1 
2 

1 


1 

1 
6 


2 
2 
4 


2 
2 




May 16 - -.- 




4 


May 24I 


1 


1 


4 










Total number of diseased bugs, 53. 

BOTTLES 21 TO 


30. 


Bottle No 


21 


22 


23 


24 


25 


26 


27 


28 


29 


30 








Number of diseased bugs. 


May 10 
























1 


2 






3 


1 
2 
10 


1 


1 






May 16 . 








1 


May 24,. 


17 


6 


11 


1 


3 


15 


6 


15 


9 







Total number of diseased bugs, 105. 

It is possible that bottles 21-30 had more spores attached to them 
than those in the other bottles, but that the spores possessed viru- 
lence is shown by the results in mortality. 

Experiment Jf, — This experiment was begun May 17. Forty-eight 
screw-capped bottles, each containing an equal amount of earth, 
were sterilized in an autoclave. Twelve adult chinch bugs were then 
•placed in each bottle. Twenty-four bottles were kept as checks 
(uninoculated) , and 24 were inoculated as follows: Thirteen bottles 
by allowing bugs to crawl over spores from a culture and 11 bottles 
by scattering similar spores into the bottles with a camel's-hair 
brush. The brush was rolled in a mass of the spores in a petri-dish 
culture and then struck sharply against the lip of the bottle. A cloud 



24 



THE WHITE-FUNGUS DISEASE IN KANSAS, 



of spores was thereby dislodged, which so filled the bottle that every 
chinch bug must have come into contact with them. 
On May 22 the results were as follows: 



Bottle No 


1 


2 


3 


4 


5 


6 


7 


8 


9 


10 


11 


12 


13 








Number of diseased bugs. 


Inoculated 


4 



8 



10 
1 


12 



12 
1 


11 



12 



10 



11 
1 


11 



S 9 
2 1 


^?, 


Checks 


1 






Bottle No 


14 


15 


16 


17 


18 


19 


20 


21 


22 


23 


24 






Total. 




Number of diseased bugs. 


Inoculated • - 

Checks - • 


7 



12 

1 


10 



6 



5 



9 



8 

1 


10 



11 

2 


,0 

1 


9 



227 
12 



Expei^ment 5. — The last of the series on virulence was begun on 
July 14, this late date being selected for the reason that the cultures 
then in the laboratory had been running saprophytically since the 
original isolation of the fungus in January, 1910, and there was a 
question whether such prolonged cultivation on artificial media had 
had the effect of lowering the virulence and hence weakening the 
power of the fungus in attacking chinch bugs. 

As the latter part of July was the time in which the field experi- 
ments were terminated, it was pertinent to know whether the fungus 
used in field inoculation during June and July had retained the 
parasitic nature evidenced by the earlier experiments of this series 
on virulence. Experiment 5 was arranged to compare inoculations 
with artificially grown fungus with natural infection. Natural infec- 
tion was presupposed, since there was no field found where Sporo- 
trichum did not exist naturally to some, even though to small, extent. 
The method of procedure differed but slightly from that in experi- 
ment 4. Forty screw-capped bottles were partially filled with 100 
grams each of moistened and thoroughly mixed earth. They were 
then sterilized with 15 pounds pressure in an autoclave. Ten adult 
chinch bugs were placed in each bottle. Twenty bottles were infected 
by the camel's-hair brush method described in experiment 4. The 
other 20 were checks. 

The bottles were watched, and it was soon noticed that Sporo- 
trichum was appearing among the treated bugs at a much faster rate 
than among the untreated. The disease in the checks was undoubt- 
edly introduced with the bugs and was present on them when they 
were collected from the field. But the same amount of natural 
fungus approximately would be present in the bugs in the inoculated 
bottles, so that final results would be but little affected. 



INFECTION EXPEEIMENTS IN LABORATOEY. 



25 



The bottles were opened July 23 and the number of Sporotrichum- 
covered buss ascertained. 



CHECK BOTTLES. 



Bottle No 


1 


2 


3 


4 


5 


6 


7 


8 


9 


10 


11 






"NTiiTnhftr nf HisfinsfiH hng<! 





1 




















1 


1 


\ 






Bottle No 


12 


13 


14 


15 


16 


17 


18 


19 


20 


Total 






Number of diseased bugs 





1 





1 











1 


2 


o 









INOCULATED BOTTLES. 



Bottle No 


1 


2 


3 


4 


5 


6 


7 


8 


9 

2 


10 

1 








Number of diseased bugs 


6 


5 


6 


7 


3 


3 


8 


4 








Bottle No 


12 


13 


14 


15 


16 


17 


18 


19 


20 


Total. 




Number of diseased bugs 


1 


1 


1 





1 


2 





4 


6 


fii 









The five experiments pointed uniformly to one conclusion — that no 
mistake had been made in adopting artificially grown fungus in pref- 
erence to that found on dead bugs, especially when it was found that 
so much more could, with certainty, be procured. In a great major- 
ity of instances in which field inoculation was undertaken the natural 
presence of the diseased bugs in large amounts would have rendered 
ineffectual the scattering of the comparatively few bugs obtained 
from infection boxes. 

Dr. M. A. Barber, director of the clinical laboratories of the uni- 
versity and inventor of the technique by which single bacterial cells 
or spores may be manipulated at will, conducted some inoculation 
experiments that shed light on the problem of virulence and infec- 
tiousness of artificial cultures. He has outlined his work below : 

In the following experiments spores of Sporotrichum glohuliferum 
were inoculated directly into the bodies of chinch bugs by means of 
very fine pointed pipettes made of hard Jena glass. Very small 
quantities of an emulsion of spores in salt solution were drawn into 
the tip of the pipette by means of a suction on a rubber tube attached 
to the blunt end of the pipette. The point of the pipette was then 
inserted into the leg or abdomen of the insect and the spores forced 
in by gently blowing into the rubber tube. Inoculation was done 
under a large simple lens. The same technique has been successfully 
used in the inoculation of flies, cockroaches, and other insects with 
bacteria and various microorganisms. 

The experiments with chinch bugs were undertaken largely for the 
purpose of testing the technique, and the number of series undertaken 



26 



THE WHITE-FUNGUS DISEASE IN KANSAS. 



was too small to warrant any definite conclusions. The results, how- 
ever, indicate that chinch bugs may survive the injury made by the 
pipette, that direct inoculation into the body is more surely followed 
by infection than exposure to spores placed only on the surface of 
the body, and that introduction of spores into the abdomen gives a 
larger proportion of infections than inoculation into the leg. 

One series is given below as an example of the method employed. 
It differs, of course, from the natural one, but the technique is of 
service in testing the conditions of infection, as the virulence of 
spores grown artificially on culture media or the resistance of insects 
kept under different conditions or in different stages of growth. 

All chinch bugs used in the experiments were taken from the same 
lot, and all were inoculated with an emulsion in physiological salt 
solution of spores of S'porotricJium globulijerum taken from a 21-day 
agar culture. 

Twelve or more insects are included in each group. This culture 
was one derived from a series of transfers beginning with an original 
transfer made from a diseased chinch bug in January, 1910. 



Group. 


Inoculated May 26. 


May 31. 


June 2. 


June 6. 


1 


In legs; at least con- 
tact of spores with 
injured surface. 


No apparent fun- 
gus growth; 
some bugs still 
living. 


Beginning of 
growth, 'appar- 
ently Sporotri- 
chum; growth 
first appearing 
on leg; all bugs 
dead. 


Majority of bugs 
covered with 
Sporotrichum. 


2 


Spores placed on un- 
injured leg. 


No fungus growth 
apparent; some 
bugs still living. 


No fungus growth 
apparent; some 
bugs still living. 


Several bugs with 
Sporotrichum; 
some still liv- 
ing. 


3 


Inoculated in abdo- 
men. 


Beginning of fun- 
gus growth; all 
bugs dead. 


All or nearly all 
covered w"ith 
Sporotrichum. 


Apparently a 1 1 
covered with 
Sporotrichum. 


4 


Controls; no spores 
added. 


Apparently no in- 
fection; some 
bugs living. 


Apparently no in- 
fection; some 
bugs living. 


Apparently no in- 
fection; at least 
one bug living. 



Artificial. Infection — Field Experiments. 

The fungus material used in the following experiments was grown 
in the laboratory by methods already described. In the field the 
dried petri-dish cultures were rubbed up with dry earth, making a 
mixture that was light-colored, due to the large admixture of spores. 
The mixture was dusted directly on the bugs on the infested wheat 
or corn, and on the ground at the base of wheat, where the insects 
congregated. 

Shading exferiments. — To test the effect of shade, artificially pro- 
duced, on Sporotrichum in its parasitic relation to chinch bugs, small 



ARTIFICIAL INFECTION FIELD EXPERIMENTS. 27 

plots of shade-giving, low-statured plants were set out in certain 
badly infested wheat fields. Shading experiments of a different na- 
ture were tried in cornfields, but these will be discussed in another 
place. 

The plots were set out to beans or cowpeas, as the case might be 
(the former proving the better), and were 50 feet square. A row of 
beans a foot wide formed the four sides of the square, and four rows, 
each a foot wide, were planted across the square, 10 feet apart, so 
that they would intersect the wheat rows at right angles. The ap- 
pearance of each plot when finished was that of a gridiron. 

The original purpose was to provide such shade that chinch bugs 
traveling along the wheat rows would encounter the shade and the 
moisture conditions of the bean rows. The beans were planted 
thickly, so that when the plants grew to 8 or 10 inches in height the 
ground beneath them was moist when that elsewhere would be dry. 
It was hoped that the wheat would come into close connection with 
the bean rows, but this was not always the case. It was hoped, also, 
that the bugs would seek the shade, and thereby enter conditions 
which would favor the development of Sporotrichum. It was found, 
however, that the bugs did not collect under the beans to any extent, 
nor did they appear to pass across the rows except in a few instances. 
Hence the infection sown among the beans, or cowpeas, failed to gain 
a favorable opportunity to come into contact Avith the bugs. While 
as a shading experiment the bean plots were of no value, they served 
a most excellent use as areas of infection or centers of infection. As 
they were laid out directly in the wheat they contained chinch bugs 
in as great numbers as the wheat outside them. Fungus was sown 
in them in large amounts, so that one might expect one of two results : 
(1) The chinch bugs inclosed by the plots showing greater mortality 
by Sporotrichum; (2) the plots becoming centers of field infection, 
with the greatest effect seen nearest the plots themselves. In most 
instances the experimental areas exhibited spontaneous outbreaks of 
Sporotrichum, and, with the fungus sown artificially, the plots con- 
tained an extensive amount of infectious material. In each experi- 
mental field, where a 50 by 50 foot experimental area was inoculated 
with fungus spores, a check area, or plot, similar in every way, was 
laid out from 100 to 200 yards distant. By comparing the two plots 
the effect of the artificial infection could be judged better. 

The spread of the disease, if any occurred, was watched not only 
in the experimental areas but in other parts of the field and in fields 
at distances from a fourth of a mile to several miles. 

Artificial infection — Localities in which field experiments were 
conducted. — In the selection of fields for artificial infection the first 
prerequisite was the presence of large numbers of chinch bugs, since 
a contagion of any kind spreads faster, other things being equal, 



28 THE WHITE-FUNGUS DISEASE IN KANSAS. 

where congestion is greatest. A second desideratum was the scatter- 
ing of the centers of field work in such a manner that results would 
be general for the entire infested area of Kansas rather than local in 
character. Varied conditions would then be encountered; for ex- 
ample, one section would have less rainfall; another lighter soil; 
one with Sporotrichum abundant in the soil, another with it scarce. 
As to extremes of latitude, one county in the northern portion of the 
State and three along the southern border were chosen. With these 
things in mind, the following sections of the State, with the towns 
near which activities were carried on, were selected : 

South-central section : Wellington, Sumner County. 

Middle-central section : Newton, Harvey County. 

North-central section : Lebanon, Smith County. 

Southeastern section: Cherryvale and Independence, Montgomery County; 
Fredonia, Wilson County ; Parsons, Labette County ; Thayer, Neosho County. 

Middle-eastern section : Colony and Garnett, Anderson County ; Lebo, Coffey 
County. 

Field notes covering observations made at intervals were, of course, 
carefully taken. Eecords of precipitation were furnished by a local 
or near-by observer in the Weather Bureau service. In a few in- 
stances rain gauges were provided and records kept for the immediate 
vicinity of the experimental farms. 

The method of procedure in each locality was essentially the same. 
Until wheat harvest, artificial infection was confined principally to 
the wheat fields, though in a few instances oats and young corn, when 
badly infested, were also treated. Fields in which chinch bugs were 
particularly numerous were deemed best suited for artificial infection. 
Several such fields were generally selected, the owners' consent ob- 
tained, and either 50-foot plots laid out or inoculation made of some 
definite corner, side, or marked spot. 

The experimental fields were examined before any infection was set 
out, to ascertain, if possible, the presence of the fungus naturally in 
the soil. Direct observation of fungus-covered bugs was one kind of 
evidence used. If these were lacking, as was the case earlier in the 
spring, wlien dry conditions prevailed over the entire State, sterile 
bottles filled with bugs and earth were used, with the expectation that 
the fungus would break out spontaneously on the bugs when in moist 
conditions under confinement. In almost every instance the experi- 
mental field was thus shown to contain Sporotrichum before any 
spores were sown artificially. The only reason for continuing with 
the artificial inoculation experiments was to determine whether the 
extra amount of infectious material added would induce an epidemic, 
when under normal conditions only a slight outbreak would occur. 

Check fields, uninoculated and at distances varying from a quarter 
of a mile to several miles, were carefully observed, as they consti- 
tuted the key to the situation. 



ARTIFICIAL, INFECTION FIELD EXPERIMENTS. 29 

It will not be necessary to give the field notes for all the localities 
in full, since a few will suffice to show how the work was conducted. 

Sumner County. — Attention was first called to the vicinity of Wel- 
lington, in which chinch bugs promised to be extremely troublesome. 
Collections of the bugs early in the spring confirmed the report. 
Sporotrichum was known to be present in the soil because of its 
presence in the bottle culture used as tests. 

The use of three wheat fields was kindly permitted by Messrs. 
Lynch, Banks, and Russell. Other farmers offered the use of their 
fields, but the three mentioned were found to be the most favorable 
in point of wheat prospects and numbers of bugs. The experiments 
on two of them will be described in detail. 

Experiments in Mr. LyncKs -field. — Two plots, 50 feet square and 
planted gridiron fashion, with a dwarf variety of beans, were set 
out about 150 yards apart in the wheat field northwest of the Lynch 
residence. The plots contained approximately the same number of 
bugs, but the wheat was ranker in one than in the other. It grew 
finally so tall and close that its shade greatly exceeded that given by 
the beans. The beans were sown in the latter part of April, but it 
was not until about May 18 that the plants were high enough to make 
sufficient shade. On May 18 the field was examined for chinch 
bugs dead of Sporotrichum that existed naturally in the soil. They 
were found in both plots ; also in other parts of the field. The part 
selected for artificial infection w\as near the center of the field, by an 
old strawstack. The check plot was that containing the ranker 
growth of wheat. Owing to the shade in the check, the conditions 
for fungus development were deemed better, but, on the other hand, 
the plot with the thinner growth contained more spores, owing to 
the artificial infection. About 20 dried petri-dish cultures were 
stirred into a bucket of dry soil, and the mixture, whitened with the 
spores, was sown along the wheat rows and under the beans. There 
was no doubt but that the swarms of bugs around the wheat came 
into close contact with the infection. In addition, they jostled almost 
continuously the whitened corpses of bugs, already dead of the Sporo- 
trichum disease. 

A shading experiment, in which straw was used, was conducted 
near the infected spot. Small piles of straw were laid both between 
the wheat rows and around the wheat. Fungus-infected earth was 
then liberally sown in the straw and under it. The straw was util- 
ized to keep the ground beneath moist, so that if bugs frequented 
the straw to any extent they would find conditions more favorable 
than out in the open. Many would contract the disease, perhaps, 
and then leaving the piles die in other locations, thus scattering the 
infection. 

On May 25 a second and thorough infection of the previously 
infected plot and straw piles was made. At the same time results 



30 THE WHITE-FUNGUS DISEASE IN KANSAS. 

of the previous inoculations were looked for and the general situa- 
tion examined. Diseased bugs were found in both plots, more being 
found in the check. Recent rains that had moistened the soil now 
showed no effect on the surface, except where the wheat was rank. 
Bugs were dead in all parts of the field, and in many places the dead 
bugs were as numerous as in the infected plot. Under the straw that 
had been packed around the wheat there were more diseased bugs 
found than anywhere else ; but there were no more, apparenth^, near 
the piles than at a distance from them, so that the infection had not 
spread, to any appreciable degree, at least. 

Chinch bugs, young and old, swarmed along the wheat rows, with 
no more dead ones in the infected plot than outside of it, or in 
many other parts of the field. Clearly the artificial infection had 
yielded no results. The wheat was showing the effects of dry 
weather as well as the attacks of the bugs. It was found that the 
beans gave entirely negative results. While the ground remained 
moist longer beneath them, the chinch bugs did not frequent them 
to any extent. 

On June 12 the Lynch field was again visited. The greatest num- 
ber of living, as well as of diseased bugs, was found in the check 
plot, with its rank wheat. Conditions elsewhere were about as they 
were on the previous visit. The wheat had turned yellow and was 
nearly ready for harvesting. In the 25 days since the first infection 
in which the artificially sown fungus had been allowed to act, the 
moist conditions resulting from two periods of precipitation had 
favored the growth of Sporotrichum. On the whole, however, the 
period had been dry. The drought had not prevented a general 
spontaneous outbreak, but it probably checked its severity. The 
artificially infected plot had not only the bugs dead of the Sporo- 
trichum naturally present, but it had relatively enormous quantities 
of culture fungus, so that as to intensity of infection it was much 
more thoroughly treated than would have ever been possible with 
diseased bugs, or than it would have been had the spores been spread 
over an entire field. The artificial inoculation was a failure in that 
it did not perceptibly decrease the number of bugs in the 50-foot 
plot, when compared with the area about it and with the check ; nor 
did the fungus spread from the treated plot or the straw piles. The 
check had more diseased bugs than the treated plot, but this may 
have been due to the moister conditions produced by shade or to 
greater numbers in the first place. Apparently the presence or ab- 
sence of the culture fungus did not affect the problem. 

As check fields to the Lynch fields, three were examined, the near- 
est being about a fourth of a mile distant, the other two one-half 
and three-fourths of a mile distant, respectively. None had been 
artificially infected, yet each contained diseased bugs. 



AETIFICIAL INFECTION FIELD EXPERIMENTS. 31 

Experiments on Mr. Banks's place. — The field offered for experi- 
mental use was on a slope south of the house. Like the Lynch field, 
one had contained a rank growth and the other a thin stand of wheat ; 
but the rank growth was denser and the thin growth was poorer than 
that found on Mr. Lynch's place. In order to balance matters the 
bean plot set out in the dense growth of wheat was used for artificial 
infection, while that in the thin growth served as a check. It was 
noticed that diseased chinch bugs were present in all parts of the 
field before any fungus had been distributed. The first inoculation 
was made May 18. Cultures were mixed with the earth and sown as 
in the Lynch field. The beans were useless, as they were shaded by 
the wheat. The ground was moist in both plots, and especially in the 
treated one. Observations were taken May 25. Both plots, as well 
as the remainder of the field, contained diseased bugs, but the dense 
growth showed the greatest number, outside the plot as well as in- 
side. Had not the Lynch field served as a kind of control these 
results might have been regarded in part as favorable to artificial in- 
fection. On the same date (May 25) a second distribution of fungus 
was made in this plot. Final observations were taken June 12, but 
there was no change in the results. The favorable conditions of shade 
and moisture favored Sporotrichum. No matter whether fungus 
spores were added or not, about the same number of bugs died, and 
there were more than in a plot where the sun had a better access to 
the soil and where conditions were drier. The fungus showed no 
tendency to spread. The bugs had begun to migrate into the neigh- 
boring oats and the cornfields. A wheat field about a fourth of a mile 
distant, untreated, contained many diseased bugs. Other check fields 
were the Cann place and the Euggles place, both about 3 miles dis- 
tant. Diseased bugs were plentiful in all of them. 

Weather conditioiu. — Statistics as to humidity and precipitation 
for the district around Wellington were kindly gathered by Mr. 
E. O. G. Kelly and his associate, the former an assistant in the Bu- 
reau of Entomology of the United States Department of Agriculture. 
The recording instruments were kept at the station, which was 
approximately the center of the area that would include the three 
experimental fields. Observations covered most of May and June, 
during which field investigations were going on. Total precipitation 
recorded by Mr. Kelly, 6.13 inches. The total for April, May, and 
June at Rome, a few miles south, was 6.27 inches. 

The spring and early summer were unusually dry, as the average 
monthly rainfall for the district around Rome was lower than the 
normal by the following amounts: April, 1.59 inches; May, 1.23 
inches; and June, 3.32 inches. In sj^ite of the diminished precipita- 
tion, however, spontaneous outbreaks of Sporotrichum occurred all 
about Wellington, no field containing chinch bugs failing to exhibit 
the whitened, fungus-covered bugs. 
10944°— Bull. 107—11 3 



32 THE WHITE-FUNGUS DISEASE IN KANSAS. 

North-central section, Smith County, Lehanon. — For this section 
Lebanon was selected as a favorable place for carrying on some field 
experiments. Accordingly, one of the writers went to Lebanon, April 
18, and with the assistance of Dr. W. C. Bower and Mr. Charles 
Isom selected five fields in which to experiment. The details of the 
work in one field only, that of Charles Sargent, will be given, as the 
results in all these experiments were the same. 

At the time of our visit it was very dry. On the 20th a severe 
dust storm prevented us from going to the country. The bugs were 
plentiful in all the fields visited, but no diseased bugs were found. 

Eocperiments in Mr. Sargenfs -field. — On April 21 Mr. Sargent's 
field was examined for diseased bugs, but none was found, though 
living ones were abundant. On May 10 a supply of Sporotrichum 
was sent to Mr. Sargent with which to infect his field. On May 12 
it was mixed with earth and distributed along a small draw where 
bugs were thick, wheat was rank, and moisture conditions were fa- 
vorable. Small bunches of straw were also infected. The field was 
examined May 31 for results. Occasional dead bugs could be found 
in all parts of the field, but, on the whole, diseased insects were scarce. 
There were more of them, however, in the draw where the infection 
was placed than elsewhere, but this might have been caused quite as 
much by the more favorable conditions there as by artificial infec- 
tion. There seemed to be a few more diseased bugs also in the im- 
mediate vicinity of the bunches of straw than at a distance of a few 
yards away, but the difference was so slight that the experiment could 
scarcely be called successful. On the same date Mr. Moore's field, 
1 mile south, and Mr. Waddles's field, 1 mile north, were inspected, 
and diseased bugs were found in both of them, though they had not 
been infected artificially. There was no appreciable difference in 
respect to the number of dead bugs in the fields. 

On this date (May 31) a second distribution of fungus was made 
in the draw. Spores were dusted directly from the cultures upon 
the bases of the wheat, where the bugs were most plentiful. This 
was done in two definite areas, which were carefully marked. 

During wheat harvest, June 28, the field was again visited. Dis- 
eased bugs were much more numerous all over the field than at the 
time of the previous visit. Especially was this true along the draw 
where in some spots the diseased bugs were thick enough to whiten 
the ground. In and around the two infected spots, however, there 
were no more diseased bugs than in equally favorable spots elsewhere. 
Young bugs were still swarming in the wheat in vast multitudes, so 
that the fungus did not materially help the field, though a good many 
died, especially among the old bugs. Two factors may have been at 
work in the outbreak of Sporotrichum; one, the artificial infection, 
the other, the favorable conditions acting in conjunction with the 



AKTIFICIAL INFECTION FIELD EXPERIMENTS. 33 

fungus naturally present in the soil. In analyzing the factors, the 
distribution of the dead bugs was taken to be the important element. 
A search of the field showed that they were thicker in some parts than 
in others, but numbers were related to conditions of moisture rather 
than to centers of artificial infection. Hence it is not improbable that 
the situation would not have been appreciably altered had no fungus 
been sown in the field. Other fields near Lebanon in which no Sporo- 
trichum had been introduced, or at least not until a later date, were 
used as checks, and particularly the Moore field, 1 mile south, and the 
Waddl&s field, 1 mile north. They were examined carefully on the 
same dates as the Sargent field, and at no time was there any percep- 
tible difference, so far as diseased bugs were concerned, in the three 
fields. All the check fields contained diseased bugs in considerable 
numbers, especially where the conditions were particularly favorable. 
Owing to artificial infection of the Sargent field before the time was 
ripe for a general spontaneous outbreak of Sporotrichum, the occur- 
rence of the outbreak in this field had all the appearance of being due 
to the sowing of the fungus. To a casual observer the success of arti- 
ficial infection would have been regarded as indisputable, though of 
course partial, since not all the chinch bugs were killed. It is likely 
that some of the "successes" reported by farmers in former years 
were due to a misinterpretation of such appearances of Sporotrichum 
among the bugs. 

The results of the experiments at Lebanon showed the importance 
of moisture conditions as factors in the development of the Sporo- 
trichum disease, especially in a dry season, and at the same time 
how unimportant a factor is the sowing of the fungus spores. 

Total precipitation at Lebanon for the months of April, May, and 
June, 1910, 6.85 inches, which was 2.08 inches less than the average. 
For May, however, the rainfall was 0.04 inch greater than the aver- 
age. The greatest deficiency in precipitation was during April. 

Southeastern section^ Montgomery County^ Gheriyvale. — Three 
farmers near Cherry vale kindly offered the use of their wheat fields 
for experimentation. They were Mr. Metcalf, Mr. Benham, and Mr. 
Darling. The vicinity of Cherryvale was badly infested with bugs 
and hence offered a favorable opportunity for experiment. The east- 
ern portion of the State, moreover, exhibited better climatic condi- 
tions, owing to greater rainfall and humidity. 

On April 27 collection of bugs and earth in sterile jars was made 
from each of the three fields mentioned above. Sporotrichum de- 
veloped readily, thus showing the presence of the fungus naturally in 
the soil. On the Benham and Darling places, 50-foot plots of the 
usual type were set out to cowpeas and placed about 100 yards apart. 

The cowpeas did not prove of any advantage as to shade, and so 
the idiots were used to mark the areas for infection and check. 



34 THE WHITE-FUNGUS DISEASE IN KANSAS, 

Experiments in Mr. Metcalfs field. — This field was located about 
4 miles north of town and was the worst infested place seen around 
Cherryvale. No plots were set out, but the infection of it was left 
in the hands of Mr. Metcalf himself, who scattered the fungus gen- 
erally over the field. On May 2 a large package of fungus culture 
was shipped, with instructions as to mixing with soil and distributing 
through his field. On May 13 a second lot was sent, and a third 
shipment was made May 22. 

On May 26 a visit was made to the field. Up to this time there 
had been two artificial distributions of the fungus culture, and also 
several of diseased chinch bugs taken from an infection box. Living 
bugs were exceedingly numerous, and the conditions for their destruc- 
tion by Sporotrichum were to all appearances ideal, as rainfall, a 
moisture-retaining soil, and high humidity for much of the time 
conspired to render the spread of the fungus easy. An outbreak of 
Sporotrichum occurred early in May, and by May 26 had succeeded 
in killing many thousands of chinch bugs, so that they were plainly 
in evidence on the ground all over the field, yet so numerous were 
the living ones that the dead ones were at anj^ time only a small per- 
centage. Had not the check fields been watched, the outbreak might 
have been attributed directly to an artificial infection. In fact, it 
seemed to Mr. Metcalf, at least at first, that the fungus he had sown 
was quite successful, especially as he had put it out before any appear- 
ance of diseased bugs was manifest. But spontaneous outbreaks 
occurred in all the fields examined around Cherryvale at about the 
same time, and no difference was noticed as to whether a field had 
been artificially infected or not. One can readily see how a farmer, 
observing the state of affairs merely on his own place, would be con- 
vinced of the success of his artificial infection and would send in his 
report accordingly. 

So plausible was the evidence to Mr. Metcalf that it was only 
with difficulty that he was convinced after visiting a check field 
owned by Mr. Steinburger and located 1^ miles distant. The Stein- 
burger field was nearly as badlj^ infested as was Mr. Metcalfs, and 
the diseased bugs appeared more numerous than on his own, though 
no artificial infection had been used. 

On this date (May 26) the Metcalf field was artificially infected 
by fungus culture for the third time. The amount of fungus added to 
the field was, of course, a small proportion of that found naturally on 
the thousands of dead bugs scattered through it. On June 23, about 
harvest time, the field was again visited. Conditions w^ere found to 
be about the same as on the previous visit. Two check fields other 
than Mr. Steinburger's, lying about 2 miles distant, were used for 
comparison. Both had numerous living bugs and as extensive spon- 
taneous outbreaks of Sporotrichum as any field around Cherrj^vale. 



ARTIFICIAL INFECTION FIELD EXPERIMENTS. 35 

Montgomery County^ Independence. — The experiments conducted 
at Independence were under the supervision of Leslie A. Kenoyer, a 
graduate in science of the University of Kansas. Mr. Kenoyer lived 
at home, on the farm, while carrying on his work, and was therefore 
able by constant residence to watch the progress of events in a most 
satisfactory manner. His observations, however, were checked up 
from time to time. His final report is given below in full. 

Mr. L. a. Kenoyer's Report of His Experiments with Sporotriciium a^td 

THE Chinch Bug. 

My observations on chinch bugs near Independence, Montgomery 
County, Kans., covered a period of nearly three months — from March 
20 until June 14, 1910. 

The bugs were found to occur in most grain fields. They were, 
as a rule, most abundant near the borders of the field, and especially 
adjoining hedges of Osage orange. These hedges are numerous in 
this county and they appear to be excellent harboring places for the 
bugs, chiefly, it appears, by reason of the weeds and grass which 
collect there. Even spring burning does not seem to destroy the 
bugs. 

Dr. F. H. Billings and I planted bush beans around several selected 
plots of grain about April 15. The plots chosen were 50 feet 
square. A trench 1 foot wide was made around each and four simi- 
lar trenches were placed across the square at intervals of 10 feet — 
the whole having the form of a gridiron. The beans were thickly 
sown in the trenches. In the Evans and the Page wheat fields two 
plots in each were thus arranged, the one to be infected and the other 
to serve as a check. In the Kellenberger oat field one plot was 
planted and kept infected. In the Evans wheat field two plots of 
the same size and appearance as those planted to beans were laid 
out by means of strips of old straw 1 foot broad. One was infected 
and the other left as a check. In a neighboring field «small piles of 
straw and of fresh weeds were placed at intervals and kept infected. 

The end sought in these experiments was a method of supplying 
shade and moisture enough to encourage the development of the 
fungus. 

Fungus grown at the University of Kansas on a pref)aration of 
corn meal and potato extract was pulverized, mixed with dry dust 
or sand, and scattered in the bean rows and strips of straw. 

In the Page field the plots were planted just south of a hedge, 
along w^hich were a good many bugs in the spring. The plots were 
about 60 rods apart. The west one was infected May 7 and May 14. 
As the bugs seemed to diminish in numbers along the hedge, no more 
fungus was placed in this field. At the last examination, June 11, a 
few living and a few fungus-covered bugs were found in both 



36 THE WHITE-FUNGUS DISEASE IN KANSAS. 

places. Both living and dead seemed to be rather more numerous in 
the noninfected plot, but the results were indecisive. 

Fungus was sprinkled on the bean plot in the Kellenberger oats 
field May 7, May 14, May 26, and June 4. Bugs did not become 
plentiful in this field and very few young ones appeared. There 
were a few more, both living and diseased, in and about the infected 
plot than elsewhere. .But wherever there were living bugs, diseased 
ones could be found by a little searching. 

In the Evans field the bean plots were located just north of a 
hedge and about 40 rods apart. The east plot was infected on the 
above-mentioned dates. Bugs continued very numerous all spring 
in this field. Hordes of young ones appeared about the middle of 
May and their influence, added to that of an early spring drought, 
killed much of the wheat before it was ripe. Fungus developed all 
over the field so freely that by the middle of June from 50 to 100 
dead and whitened bugs could frequently be found around the bases 
and on the roots of a single hill. While the fungus appeared in all 
parts of the field it was in general more abundant at the west end, 
so it chanced that the uninfected bean plot showed decidedl}^ more 
fungus than the infected one. 

The " east " straw plot was infected on the same dates as the bean 
plot and the " west " plot was left as a check. On neither one were 
the bugs as numerous as along the side of the field on which the 
beans were planted, but both living and dead bugs were to be seen in 
about equal numbers in the infected plot and the check plot. 

The piles of straw and those of weeds were likewise infected, but 
without any appreciable increase in the death rate of the bugs. 

Although the beans had made a veiy good shade before harvest 
time, the bugs showed no marked tendency to seek the shade. They 
are more active on sunny days than in cool, cloudy weather, and 
when crawling from hill to hill they appear to seek sunshine rather 
than shade. 

After the wheat had ripened the bugs crawled up the bean bushes 
in considerable numbers, and many dead fungus-covered bugs could 
be seen adhering to the leaves of the plants and to the young beans. 
Famine had evidently aided the plague in this case. But here again 
there was no difference in favor of infected portions. 

To determine the efficiency of the distribution of dead bugs in 
fields I selected an oats field on the Evans farm, one- fourth of a 
mile from the experimental wheat field. A strip of about 3 by 10 
yards was sprinkled on May 25, May 28, and June 4 with diseased 
bugs grown in culture boxes. Developments on this portion were in 
no way different from those on the remainder of the field. 

On April 20 a pint fruit jar was scalded and half filled with bugs 
and soil from the Evans wheat field. Sporotrichum developed in 



AETinCIAL INFECTION FIELD EXPERIMENTS. 37 

from 8 to 10 days, showing quite conclusively that the spores were 
present in the soil. 

In a field of wheat and in one of rye, west of the infected fields 
and about three-fourths of a mile distant from any of them, diseased 
bugs were found in the early part of June in as great numbers as in 
the Evans field just mentioned. The chance of material from my 
infections having reached these fields was very improbable. Several 
other fields were examined and none was free from infected bugs 
where bugs were plentiful in the period preceding harvest. But 
the proportion of diseased bugs varied considerably from field to 
field. And apparently in no case had the fungus produced an epi- 
demic sufficient to materially reduce the number of bugs or to save 
the crop. 

My experience with infection boxes was not such as to greatly 
encourage the infection idea. Living bugs were confined with dis- 
eased ones in boxes of moist earth for weeks at a time, and only a very 
few became infected. Later in the season, when the disease became 
common in the fields, it spread more readily in my boxes. 

My observations lead to the following conclusions : 

1. Sporotrichum occurred naturally in the soil of all of the fields. 

2. The distribution of the spores or of spore-covered bugs in a 
field had no noticeable effect upon the dying of bugs. 

3. Bugs died spontaneously when the weather was sufficiently moist 
and when the ripening of the grain diminished their food supply. 

4. Spontaneous infection did not spread to such an extent as to 
materially benefit the crop. 

The results attained in the precedinggreport were confirmed by ob- 
servations made during the experiments. The results fully accord 
with those obtained elsewhere, and are of particular value because of 
the favorable moisture conditions and the larger number of chinch 
bugs. In the Evans field the young bugs suffered more severely by 
attacks of the fungus than in any other field investigated. 

Weather conditions for Cherryvale and Independence. — The 
weather statistics for these two centers of experimental work were 
gathered by Mr. F. L. Kenoyer, of Independence, and we hereby 
express our thanks to him for his kindness in taking humidity read- 
ings and furnishing a copy of the precipitation record. During the 
month of May and the fore part of June, southeastern Kansas had a 
rainfall in excess of the average and a relatively high humidity. 
The soil in this section, being mostly heavy, retained the moisture 
well. The conditions for fungus propagation seemed to be ideal dur- 
ing a part, at least, of the period of growth of the new brood of 
chinch bugs. While adults seemed to succumb first, many young 
were affected, especially at Independence. 



S8 THE WHITE-FTJNGtrS DISEASE IN KANSAS. 

The total precipitation at Independence for the months of April, 
May, and June, 1910, was 10.97 inches, which was 4.70 inches in excess 
of that of Rome (near Wellington, in Sumner County) . The rainfall 
for May alone at Independence was 6.25 inches, or about the same as 
for the three months near Wellington. The May precipitation was 
6.25 inches, or 1.44 inches in excess of the average. In addition to 
the unusual total precipitation for this month, the rainfall was well 
distributed. There were 19 cloudy days in May, and 5 partly cloudy, 
so that the month was damp for most of the time. Conditions were 
very favorable for Sporotrichum from the first week in May until 
the harvest time, and it was certain that the fungus responded by 
attacking vigorously both young and old bugs. Notwithstandmg the 
favorable conditions, there were plenty of bugs left at harvest time — 
enough to do great injury to the corn. 

Anderson County^ Colony and Garaett. — The experiments of Col- 
ony only will be outlined below. Two fields were used for experi- 
ment, but the field notes taken on Mr. Quiett's place will suffice for 
the purpose. 

Experiments on Mr. W. A. QuieWs place. — Work began on Mr. 
Quiett's place on April 20, when a field of wheat was searched for 
diseased bugs. 'While none was found, living bugs were numerous, 
and two bottles of bugs and earth were collected to see if Sporo- 
trichum would develop spontaneously. The results were negative. 
Diseased bugs were left with Mr. Quiett, so that he might start an 
infection box. On May 3 a supply of fungus culture was sent for 
field infection. It was distributed along the north side of the field. 
On May 19 the field was examined for results. Two diseased insects 
were found on the north side near the infected locality, but none 
was seen on the south side. It was evident, as in the Boone field, 
that no spontaneous outbreak had occurred. Some of the fungus had 
been placed under piles of straw, but there were no results in dead 
bugs. There had been more or less rain for about three weeks and 
the soil was wet. Another visit was made May 26, with no change in 
the condition of the field. Weather was cool and damp. Some 
fungus was placed at the base of the wheat in a small patch that 
was carefully marked. A similar patch some distance away was 
infected with diseased bugs and also marked. Some living bugs 
from the field were caught, shaken in a box with Sporotrichum 
spores, and then turned loose under a bunch of straw. The experi- 
ments on this date (May 26) were concluded by leaving a quantity 
of the fungus culture with Mr. Quiett for further field infection. 
The next inspection took place June 21. All parts of the field were 
searched for diseased bugs. Extremely few were found, and no more 
around the infected spots than elsewhere. The ground was damp 
and shaded in some places, but there were no more in evidence in 



ARTIFICIAL INFECTION FIELD EXPERIMENTS. 



39 



one place than in another, so far as could be seen. Harvest had 
begun before another visit was made, on July 12. The bugs had gone 
into some adjacent corn. Pupse were very thick on the ground about 
the base of the stalks, under bunches of crab grass and other vegeta- 
tion that afforded protection. Adults were emerging in large num- 
bers. A few diseased bugs were found in the corn where the bugs 
were collected for molting. A pile of cut corn was made in the field 
and fungus scattered in it. A second pile was made and left unin- 
fected. On July 30 an inspection showed that diseased bugs were 
still scarce, only one being found. The infected and check piles of 
cut corn and the locality immediately adjacent showed no effects of 
the infection or shading. Both piles of corn contained thousands of 
molted skins of the bugs, which might have been taken by an un- 
skilled observer for dead bugs. 

Results of experiments in Anderson County. — Conditions at Gar- 
nett and Colony were unique when compared with all the other 
places where experiments were made. Spontaneous outbreaks of 
Sporotrichum had been the rule, but at Garnett and Colony they 
were absent, or nearly so. To explain the situation, one would natu- 
rally examine the climatic conditions, since they probably have more 
to do with the propagation of Sporotrichum than any other factor. 
The following table gives some comparative data : 



Place. 



Garnett 

Oswego (Parsons). . . 

Lebo 

Rome (Wellington). 

Lebanon 

Chanute (Thayer) . . 

Independence 

Hutchinson 



May and June. 



Precipi- 
tation. 



Inches. 
n.31 

9.61 
12.46 

4.67 

6.19 
13.69 

9.21 



Mean 
temper- 
ature. 



° F. 
65.5 
68.0 
65.6 
68.8 
65.1 
65.5 
68.1 
67.1 



Garnett had an abundance of moisture, but the spontaneous out- 
break was only slight. Conspicuous outbreaks occurred at Lebo and 
Thayer, where the precipitation was greater, at Parsons and Inde- 
pendence, where it was but a little less, and at Wellington and 
Lebanon, where the precipitation was much less. The mean tempera- 
ture for the two months was below normal, but not below the mean 
temperature of other places where spontaneous outbreaks occurred, 
for example, Lebanon and Thayer. It would seem, therefore, that 
the explanation of the fact that spontaneous outbreaks in Anderson 
County were so meager can not be found in the climatic condition, 
and must be attributed to some other factor. Was it due to a scarcity 
of fimgus naturally present in the soil ? This would seem to furnish 



40 THE WHITE-FUNGUS DISEASE IN KANSAS. 

a plausible explanation at least, since our tests in nearly every case 
yielded negative results. But when large quantities of the fungus 
were introduced the results remained unchanged ; no ejDidemic could 
be started. It seems e^ddent, therefore, that the failure of an out- 
break to occur was not always due to the lack of the fungus, but to 
some other factor as yet unknown. 

If these two places in Anderson County are representative of those 
in which spontaneous outbreaks do not seem to occur, then it is evi- 
dent that artificial infection does not produce such outbreaks or any 
beneficial effects that are commensurate with the amount of fungus 
introduced and the time and expense necessary in introducing it. 

Corn-infection experiments at Cherryvale. — The field work at 
Cherryvale was more extended than at Independence and the climatic 
conditions were more favorable, especially during the first part of 
the work. The fields selected were owned by Mr. Metcalf and Mr. 
Botkins. They were separated by a wheat field, from which chinch 
bugs migrated. By the 21st of June about the first 20 rows of corn 
were badly infested. Two plots of corn were selected in the Metcalf 
field, at opposite ends of the corn rows nearest the wheat. The plots 
were surrounded by ridge barriers on which crude oil was placed. 
Each area had about as many bugs in it as the other. Both were very 
badly infested, and the corn gave promise of being quickly killed 
unless the bugs were exterminated. One of the plots was artificially 
infected with fungus culture. The spores were mixed with earth 
and dusted on the bugs. Some of the dried cultures were used with- 
out an admixture of earth. The insects swarmed on the corn in such 
compact bunches that large numbers could be easily dosed with 
fungus spores. Practically all of the bugs in the plot had an appli- 
cation of Sporotrichum. The other plot was used as a check. Each 
plot was about 40 feet long and included three rows of corn. The 
experiment continued for a week, or until the corn was completely 
killed out. The bugs were unhurt and finally escaped over the 
barrier and scattered into the new corn. 

A new type of experiment was then tried, the chief merit being the 
maintenance of extremely humid conditions. The other factors, large 
numbers of bugs and intensity of infection, were still at hand. The 
experiment consisted of cutting corn badly infested with bugs and 
piling it in heaps, bugs and all. In the Metcalf field about a dozen 
stalks composed each. The top soil under each pile was removed to 
expose the damper subsoil, Avhich thus assisted in preserving the 
dampness. The bugs repaired to the lower portions of the piles as 
soon as they were made, and there, with the moisture from the leaves, 
from the ground, or from the rain, or artificial watering, the humidity 
was high enough to insure propagating of the fungus. 



ARTIFICIAL INFECTION FIELD EXPERIMENTS. 41 

111 the Metcalf field six piles of corn were laid. Two were well 
watered and two of the remaining four were covered over with rank 
weeds to increase the shade. The last two w^ere not watered nor cov- 
ered with weeds. All w^ere thoroughly infected throughout with 
Sporotrichum. Chinch bugs swarmed inside the piles and as long as 
the corn remained reasonably fresh they apparently made no effort 
to leave. 

A similar series of piles was constructed in the Botkins field, only 
they were larger, having 40 stalks to the pile. A dozen such heaps 
w»ere made, and they were about 60 feet apart. None of the piles in 
the Botkins field was artificially infected. 

Four questions were to be decided by the corn-pile experiment: 

(1) Would the chinch bugs become diseased in an uninfected pile? 

(2) Would they become so in an artificially infected one? (3) Would 
the infected bugs leave the piles and carry the contagion to other 
parts of the field and ultimately bring on an epidemic? (4) Would 
the bugs die by sucking the juice of the corn, soured after cutting, as 
had been stated by certain farmers? 

The piles were prepared June 22. Heavy rains occurred June 25 
and 27, making the ground very muddy. Diseased bugs w ere noticed 
around the base of the corn in various parts of the field. The piles 
of cut corn were examined and a few dead bugs were found. The 
corn was very wet, and the lowest stalks and leaves in some of the 
piles were in mud. As the greater part of the leaves were still fresh, 
the bugs had not left the piles, but seemed quite as numerous as ever. 
If the juice had soured it had thus far caused no perceptible mor- 
tality among them. Molting had occurred to a considerable extent, 
and the old skins resembled dead bugs sufficiently to have probably 
caused some of the farmers to mistake them for bugs killed by sour 
juice or by Sporotrichum. The piles in the Botkins field, although 
untreated, contained more diseased bugs than the artificially infected 
ones in the Metcalf field. Conditions were probably more favorable 
in the former than in the latter case, since the corn was piled on 
higher ground and did not get so soggy. 

Thus far no effect worth mentioning from Sporotrichum was ob- 
served in any of the piles. The diseased bugs in the piles on the Bot- 
kins place served as infection for the other bugs. It seemed as 
though conditions in this field could not have been made better for 
the spread of infection, yet the number of diseased bugs was only a 
very small. fraction of the living. 

On this date (June 27) a pile of freshly cut corn infested with 
bugs was made in each field, the one on the Metcalf place being in- 
fected artificially with Sporotrichum. All of the piles were ex- 
amined on July 6. The original ones (made June 23) were found 



42 THE WHITE-FUNGUS DISEASE IN KANSAS. 

to be deserted by the bugs, and the corn dry and in some instances 
moldy. Skins of molted bugs were very numerous, and Sporo- 
trichum-covered carcasses were in considerable abundance, but aside 
from tlie latter there was no evidence of dead bugs, i. e., that might 
have been killed by sour juice, for instance. Evidently the great 
majority had migrated, leaving comparatively few dead behind as 
the result of infection by fungus. 

The corn piles made on June 27 were in good condition, the corn 
being green and fresh. Chinch bugs still swarmed through them in 
multitudes, and there were old skins and quite a number of diseased 
bugs. There were a few more diseased bugs in the Metcalf corn 
pile than in that in the Botkins field, and the difference may have 
been chargeable to the artificial infection. The percentage of 
diseased insects when compared with living, however, still remained 
very small, so that as an effective means of propagation of Sporo- 
trichum disease, the corn piles were a comparative failure. Quite 
the reverse might have been expected, since the chinch bugs remained 
exposed for over a week to infection under shade and moist con- 
ditions. With negative results under such circumstances artificial 
infection could hardly be expected to work in the open field. Almost 
every chinch bug in the corn piles must have come into contact with 
the fungus spores sooner or later, especially where artificial infec- 
tion was used. After leaving the piles the bugs transported the 
spores to various parts of the field, but there was no evidence that 
the spores took effect. 

By July 6 nearly all of the corn in the full 50 rows was destroyed. 
Infection of chinch bugs on corn by the use of fungus culture was 
made on this date and again on July 17. Cultures mixed with earth 
or used directly were employed in dusting spores on the insects. 
Final observations were made on July 28, five weeks after the first 
lot of the fungus was sown in the corn. From a practical stand- 
point everything was negative. At no time did the Sporotrichum 
disease appear to be working except in the smallest way. Perhaps 
the weather conditions were not just right, but at Cherry vale they 
were apparently right for at least part of the time and that long 
enough to have started an epidemic. 

If the relation between climatic conditions and successful fungus 
propagation, however, is so exact that not once did anything like 
a really destructive epidemic occur during all the series of experi- 
ments and observations from April till nearly the first of August, 
then farmers should not for a moment think of depending on arti- 
ficial infection or on the fungus disease at all for the saving of 
their crops. Whatever good had come from Sporotrichum as a 
destroyer of chinch bugs came of itself without the aid of artificial 
sowing of spores. 



the white-fungus disease in kansas. 43 

Remedial Measures and Conclusions. 

The University of Kansas, during 1910, sent Qut 1,363 packages 
of diseased chinch bugs at the request of farmers, with which to 
start infection boxes and artificially infect their fields. The plan 
followed was in accordance with recommendations of Dr. Snow, 
who in the nineties attempted to check the ravages of chinch bugs by 
the distribution of Sj^orotrichum glohuliferum^ the cause of the well- 
known white-fungus disease. A series of investigations, however, 
was inaugurated early in the year 1910, and continued until nearly 
the first of August, the purpose being to ascertain the practicability 
of artificial infection. 

The plan of work embraced the solution of the following prob- 
lems: (1) Determination of the extent of the presence of the chinch- 
bug fungus naturally in Kansas soil, (2) practicability of artificial 
infection of fields after the fungus was already shown to be present, 
(3) practicability of artificial infection of fields containing ap- 
parently little or no Sporotrichum, and incidentally (4) ascertaining 
so far as possible the best method of fighting chinch bugs in case it 
were proved that artificial infection with fungus is not effective. 

The work of solving the first problem fell naturally into two di- 
visions, namely, (1) examination of chinch bugs for the fungus 
disease, while they were still in winter quarters, and (2) examination 
of chinch bugs for disease after migration to wheat or corn fields. 

"VVliile gathering data for determining to what extent Sporotri- 
chum was naturally present in Kansas soil, many localities in the in- 
fested area were visited. The work began in January, 1910, and ex- 
tended well into the summer. As a result, 59 counties of the State 
were found by direct personal observation to contain the fungus. 
These counties are so well distributed over the infested area of Kan- 
sas as to leave but little doubt that those intervening are likewise 
supplied with fungus. 

The widespread occurrence of Sporotrichum over the State was 
recognized near the close of Dr. Snow's investigations, in the nineties, 
since in one of his later reports (the fifth) we read the following: 
" We may conclude from the experiments that Sporotrichum was 
pretty generally prevalent throughout the State, and that probably 
in many localities there was no necessity for its artificial distribution 
in 1895." 

The prevalence of the chinch-bug disease in Kansas soil once es- 
tablished, the next question was the practicability of sowing more 
fungus in fields known to contain it naturally. A solution was 
sought by actual field experiments in which relatively large quanti- 
ties of fungus were used, sometimes on entire fields, other times on 
small plots where, in consequence, an intensive artificial application 



44 THE WHITE-FUNGUS DISEASE IN KANSAS. 

of the infection resulted. While diseased chinch bugs were used to 
some extent in artificial infection, they proved inadequate because of 
the small amount of fungus available. Spore material for field work 
was generally obtained from cultures grown on a mixture of corn 
meal and potato extract. By the use of this medium large quanti- 
ties of fungus were propagated in the laboratory. Its spores were 
tested from time to time in order to be assured of their power to 
produce disease in living chinch bugs. 

With the exception of the experimental fields in one county 
(Anderson) there was already an abundance of Sporotrichum na- 
turally present in the soil, as manifested by the whitened carcasses of 
its victims. These were generally in such large numbers and were so 
widely distributed that it seemed utterly futile to add any more 
fungus, since it Avas such a trifle by comparison. Nevertheless, 19 ex- 
perimental fields, distributed over 5 different sections of the State, 
were treated with Sporotrichum spores. In some the artificial in- 
fection was confined to small j)lots of wheat 50 feet square, with the 
expectation that the intensive infection would start an epidemic of 
the disease that would spread and kill a large proportion of the 
bugs. But no results were forthcoming, for not only did the plots 
fail to become centers of contagion, but there was little or no ap- 
preciable difference between the treated and the untreated, or check 
plots, which were always used as a basis of comparison. General 
field infections were likewise always failures. 

Considering the 19 localities as a whole, there were all sorts of 
conditions of humidity and rainfall, also character of soil. The 
results, however, were always the same — never at best any more than 
a slightly appreciable effect due to sowing spores and never more 
than a small percentage of the bugs killed. The bugs victimized b}^ 
the fungus were as numerous in an untreated plot or field as in a 
treated one, the numbers bearing no relation whatever to artificial 
infection, but rather to climatic conditions, shade, moisture, etc. 
The evidence in every instance was overwhelming against the arti- 
ficial use of fungus, as being without effect, and hence useless, since 
the fungus naturally found in the soil really accomplished whatever 
destruction of chinch bugs there was. 

The third problem to be solved was the practicability of artificially 
treating a field with Sporotrichum when the fungus was shown to 
be scarce or, at least, ineffective. Three fields — one at Garnett, the 
others at Colony — were of this sort, and the bugs in all of them were 
liberally dosed with fungus. Small areas were treated as well as 
entire fields, and diseased bugs were used as well as culturally grown 
fungus; but scarcely any effect could be made, as measured by mor- 
tality among the bugs. No epidemic could be started nor the deatli 
rate appreciably increased, even in marked spots that were given 
specially large amounts of infection. 



REMEDIAL MEASURES AND CONCLUSIONS. 45 

Conclusions from all the experiments may be summed up as 
follows : 

1. The chinch-bug fungus is present naturally in fields everywhere 
throughout the infested ar^a in Kansas. 

2. It is present in such great abundance that any artificial distribu- 
tion of infection in a field would be too insignificant, by comparison, 
to be of practical use, 

3. Its distribution naturally through a field is much more uniform 
than any artificial distribution can be made. 

4. The amount of fungus used experimentally in both wheat and 
corn fields was so far in excess of any that would be used by the 
farmer in infecting his own fields that he could not reasonably expect 
to succeed. 

5. The fungus shows little tendency to spread from centers of 
artificial infection. The apparent rapid spread of the fungus is due 
to favorable conditions bringing it into activity simultaneously over 
considerable stretches of territory. 

6. In fields where the natural presence of the fungus is plainly 
evident its effect on the bugs can not be accelerated to any appreciable 
degree by the artificial introduction of spores. 

7. In fields where the fungus is not in evidence spares introduced 
artificially have no measurable effect. 

8. Apparent absence of fungus among chinch bugs in a field is 
evidence of unfavorable conditions rather than lack of the fungus 
spores. 

9. All the benefits of the Sporotrichum disease of chinch bugs may 
be realized by merely letting the fungus naturally present in the soil 
do the work of extermination as far as it will. 

10. Moisture conditions have much to do with the appearance of 
chinch-bug disease in a field ; artificial infection nothing. 

11. Spent adult chinch bugs succumb to attack more readily than 
younger ones, but as the old bugs have finished depositing their eggs, 
their loss by fungus disease accomplishes little else than increasing 
the amount of the infectious material. 

12. Laboratory experiments can be made to prove that artificial 
infection accomplishes results upon bugs confined in cramped quar- 
ters and without food, but in the field, where fresh and usually drier 
air prevails and food is abundant, an entirely different situation is 
presented. 

13. Advocating artificial infection or encouraging it by sending 
out diseased chinch bugs does not serve the best interests of the 
farmer, since his attention is thus diverted from other and more 
efficient methods of combating the pests. 

14. The reported successes of former years on the part of farmers 
are believed to be due to the following causes: (1) Failure to recog- 
nize spontaneous outbreaks of the disease because of previous arti- 



46 THE WHITE-FUNGUS DISEASE IN KANSAS. 

ficial sowing of infection, and also failure to use check, or untreated, 
fields as a basis of comparison, thus claiming the outbreak as directly 
uue to artificial infection; (2) failure to distinguish the skins of 
molted bugs from dead bugs; (3) mistaking the scattering of chinch 
bugs in cornfields for evidence of their death by fungus disease when 
carcasses were not present as proof. 

Approved methods of combating the chinch hug. — The long-drawn- 
out fight against the chinch bug has brought to light many methods 
of combating it, which, when properly applied, have proved very 
beneficial; but the farmers are very busy men and can not devote a 
great deal of time to this work, and for this reason it seems best to 
speak only of methods which have proved the most practical. We 
can not hope to exterminate the chinch bug from any given district 
by any artificial methods now known ; we must depend upon natural 
causes to do that, but in the meantime we can do much to stay their 
ravages. Their numbers can be greatly reduced and valuable crops 
protected from their depredations. The failure to control these and 
many other pests is not to be ascribed to the lack of practical means 
of control, but rather to the failure on the part of farmers and fruit- 
growers to avail themselves of the methods of control which have 
been worked out, and especially in the case of the chinch bug to the 
failure to secure concerted action throughout the area of infestation. 

The two seasons when practical measures can be applied are : The 
fall, after the chinch bugs have gone into their winter quarters, and 
the summer season, at the time when the bugs are leaving the grain 
fields or immediately after they have massed themselves upon the 
first rows of corn. 

Fall treatment. — Since the chinch bugs winter as adults in grassy 
places and in rubbish of all kinds, grasslands, and weed patches, 
every place where there is a possible chance for them to winter over 
should be burned off in the fall after they have gone into hibernation. 

From observations made during 1910 while collecting bugs from 
their winter quarters, it was quite definitely determined that the 
bugs very much prefer bunch grass to anything else as a place to 
pass the winter, and where such grasses are growing along fences 
and roads adjoining cornfields they will be found to harbor vast 
numbers of bugs. So, if it is impractical to burn off all grasslands, 
those adjoining cornfields should, at least, be burned. 

The burning does not necessarily kill the bugs, for they work down 
into the roots of the grass, where the heat caused by the burning is 
not sufficient to kill them, but those that escape the burning are left 
much more exposed to the effects of changes in temperature through- 
out the winter months and are likely to perish before spring. The 
drier the ground is when the burning is done the more effective will 
it prove, for when the ground is dry the grass will burn off closer 



EEMEDIAL MEASURES AND COlSrCLUSIONS. 47 

to the ground, more of the bugs will be killed outright, and the pro- 
tection for those that escape will be more effectively removed. The 
burning should not be done too early, for in that case, unless everyt, 
place where they might hibernate is burned, those bugs that escape 
destruction by the fire will have an opportunity, during the warm 
days that follow, to seek a new shelter. If the burning is delayed 
too long we are apt to have bad weather, which will interfere. 
About the latter part of November or the first of December is usually 
a good time. This is the time when there is a great need of con- 
certed action. It will do little good for a farmer here and there to 
burn, if others do not. No consideration should prevent farmers all 
over the infested area from applying the torch in the fall or early 
winter. 

Systematic burning is not to be recommended every year, for a 
large number of our most useful insects seek the same places to 
hibernate as the chinch bugs, but in years when the chinch bugs are 
apt to prove disastrous the good to be derived from destroying them 
in their winter quarters will by far outweigh the loss of some of our 
beneficial insects. 

Burning in the spring will do little good, unless it should be very 
dry and the burning be done at just the right time. The only good 
that can result from burning in the spring will come from the bugs 
actually destroyed by the burning. If the burning be done too early, 
while the ground is still frozen, or later, when the ground and grass 
is very wet, very few bugs will be killed, but should the ground and 
grass be dry and the burning be accomplished between the time when 
bugs are beginning to come up out of the roots of the grass and 
move about, and before they begin their spring flight, large numbers 
will be killed. The most favorable time in the day for burning, either 
in fall or spring, is from 10 o'clock in the morning to 3 o'clock in 
the afternoon. If the burning is done in the night, as is often the 
case, the bugs will have descended into the roots of the plants again, 
and a smaller number will be kiUed outright. 

Summer treatment. — After the bugs have become established in 
grain fields in the spring there is no practical way of destroying 
them. The best that a farmer can do is to hope for warm, wet 
weather during and following the hatching season in May and June, 
and prepare to take up the fight when they begin to leave the wheat 
fields. In making preparations for this fight the farmer should pro- 
vide himself with a quantity of coal tar from the gas works, or No. 18 
residuum asphaltum, or crude oil from the oil refinery, and either a 
knapsack spray pump or a spray pump mounted on a barrel. These 
should be provided before harvest begins, for sometimes they can not 
be procured without delay, and if this fight is to prove effective there 
must be no delay at the critical period. 
10944°— Bull. 107—11 4 



48 



THE WHITE-FUNGUS DISEASE IN KANSAS. 



The dust harrier. — The plan of the fight will necessarily depend 
on the conditions of the weather. If it should be warm and dry at 
harvest time the farmer should erect a dust barrier around the entire 
field containing the bugs, as follows: Before any of the wheat or 
other grain is cut, or, better, immediately after the first few rounds 
have been made by the binder, plow a strip around the field about 8 
feet wide. This should be harrowed or dragged to pulverize the soil ; 
then in the side of the strip farthest from the inclosed field a deep 
furrow should be thrown out with a lister, making round* corners, 
and a log about a foot in diameter and 6 feet long, to which a single 
horse is hitched, should be dragged around the field during the day 
as long as migration continues. If it is very hot and dry many of 
the bugs will perish in their efforts to cross the dust barrier lying 

otoociaogaooocjoovooeoaaoaoo 
ooooooooooCo/^ A^ " COOOOoooO 



1^. 






r^ 



"_ Z S -Lrn/^i r/ 'IS 



E uO 



K---^--^-- 



^ 



J 



Fig. 3. — Diagram illustrating the construction of the dust barrier, a. Outer edge of dust 
barrier; h, furrow; c, inner edge of dust barrier. (Original.) 

between the field and the furrow, and those which succeed in getting 
into the furrow will not be able to crawl up the dusty sides to get out. 
Many of them will be killed by the heat, and those that escape will be 
crushed by the log or smothered hy the dust of the furrow. The 
log should pass along frequently enough to keep the bugs from mak- 
ing breaches in the dusty sides of the furrow by their constant en- 
deavors to climb up. If one log does not prove sufficient two or three 
may be used, as needed. 

If the weather should remain warm and dry during the whole time 
when the bugs are leaving the field the above method will be sufficient 
in most cases. This method, with perhaps a little difference in the 
details, has been found to b© very effective, and has the advantage of 
being inexpensive and devoid of details which are necessary in other 
barriers, and it is, therefore, recommended when the weather is dry 
and hot. 



KEMEDIAL MEASURES AND CONCLUSIONS. 49 

Oil harriers. — If the weather should be wet, or if light showers 
should occur, so that it is not possible to keep the surface of a dust 
barrier pulverized and dusty, the farmer may resort to the oil barrier. 

The type of the oil barrier used in past campaigns against chinch 
bugs is the earth ridge, with a small line of coal tar on top. It has 
been thoroughly tested, and if properly maintained will prove effec- 
tive as a means of trapping and destroying the bugs in large quan- 
tities. 

The plan found most effective is that of turning a double furrow 
with a plow, and thus forming a ridge, and putting tar, etc., on top 
of this ridge. On the side of the ridge next to the small grain, 
pestholes about 75 or 100 feet apart and 2 feet deep are dug. The 
bugs are thus retarded in their march by the ridge, and, being re- 
pelled by the tar, etc., swarm along the ridge and crowd each other 
into the postholes. When the holes are nearly filled with bugs dirt 
should be thrown in and tramped down, and new holes dug to take 
their places. 

After the ridge is thrown up by the plow the top should be 
smoothed off and packed down so as to hold the tar or oil which is 
poured thereon. The sides of the furrow should also be smoothed 
so as to make it difficult for the bugs to climb up. This can be done 
with a hoe and a rake, but it is much more quickly done by using a 
drag made with a concave bottom of the form of the desired ridge. 
This should be heavily weighted and drawn by horses along on top 
of the ridge. Such a drag is easily constructed and will save much 
time and do better work than can be done with the hoe and rake. 
The bottom of the drag will scour better if covered with sheet zinc. 

Coal tar as it comes from the gas works is the best thing known 
for this type of barrier, as it does not sink into the ground readily 
and is very effective against the bugs. No. 18 heavy residium asphal- 
tum from the oil refinery was tried as a substitute for the tar in one of 
our experiments conducted during the past season and gave excellent 
results. It stands next to coal tar in its efficiency, and costs about 
the same. It could be procured at the refinery last summer at $4 a 
barrel. It will require about one barrel of the tar or asphaltum for 
every 80 rods of barrier constructed. Crude oil was also tried, and 
while it was effective for a time after being applied, it soaked into 
the ground very readily and had to be renewed frequently. If crude 
oil is used, about twice the amount given for the coal tar will be 
needed. The cost of crude oil at the refinery (including barrel) was 
$1 in 1910. 

Whichever one of the above repellents is used, it may be applied 
by using an old teakettle, coffeepot, or sprinkler with the perfo- 
rated end of the spout removed. In applying the tar or asphaltum 



50 



THE WHITE-FUNGUS DISEASE IN KANSAS. 



the operator should move along fast enough so that the line deposited 
on the ridge is about an inch wide. 

The ridge should be thrown up and the postholes dug before the 
migration begins, leaving the application of the repellent until 
actually needed. 

The oiled-ridge type of barrier has the advantage of not being 
dependent upon a complexity of conditions for its success, and of 
giving immediate results. However, in dry, windy weather, when 
much dust is blowing, the dust is apt to stick to the tar or asphaltum 
in quantities to render it ineflScient. For this reason the dust barrier 
is recommended for dry weather. 

After the barrier is formed it should be inspected daily and kept 
in good repair. The tar will have to be renewed occasionally and 
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Fig. 4. — Diagram illustrating the oiled-ridge type of barrier — b, barrier ; p, postholes. 
A partial barrier between the wheat and corn would extend from a to b. (Original.) 

upon the ridge and form a bridge over the repellent stream for the 
chinch bugs to cross. Eternal vigilance will be the price of success. 

The crude oil-straw harrier. — An experiment was tried in which 
straw dipped in crude oil was used as the repellent part of the bar- 
rier. It gave promise of success, especially when small fields were to 
be protected. To erect a barrier of this kind the farmer would need, 
besides the straw and crude oil, a tube or barrel mounted on a sled 
or wagon, a pitchfork, and a posthole digger. The oil is placed in 
the barrel or tub and the straw dipped into it and laid in a long- 
windrow about a foot wide and from 4 to 6 inches high. This is the 
barrier. Postholes are dug on the wheat-field side of the barrier 
about 75 feet apart and so that the straw somewhat overhangs the 
edges of the postholes. Loose soil or air-slaked lime on the sides of 
the openings facilitates the fall of the bugs into the postholes. 

The advantages of the oiled-straw barrier are its cheapness and 
the fact that it is not easily affected by weather conditions. Heavy 



REMEDIAL MEASURES AND CONCLUSION'S. 51 

rains tend to wash the oil off, but it can be renewed easily with a 
garden sprinkler. Under ordinary conditions the original oiling will 
j^robably suffice. 

The volatile products of the oil keep the bugs from crawling be- 
neath the barrier, and the difficulty of crawling along straws lying 
in every direction and coated with the offensive-smelling oil discour- 
ages the bugs from their attempts to crawl over. 

It is to be regretted that the oiled-straw barrier was not thought 
of soon enough to make a test of its practicability in protecting an 
entire field. A small patch of corn in a field into which the invasion 
of the bugs had already begun was surrounded by a barrier of this 
kind in order to ascertain its effectiveness. A few bugs were already 
in the corn inclosed by the barrier, but these were removed by hand 
and thrown outside. Any bugs that were subsequently found in the 
corn, therefore, presumably had crossed the barrier. The experi- 
mental corn patch lay in the direct line of march of the principal 
mass of migrating bugs. 

The barrier was prepared June 23, 1910. During the next five days 
no fresh oil was applied, and a torrential rain washed out some of the 
oil with which the straw was originally saturated, leaving the upper 
straw odorless and reducing the oil beneath, so that the odor was 
faint. As a result, a few chinch bugs were found crossing the bar- 
rier on the uppermost straws. None was passing underneath. A 
second application of oil was made with a garden sprinkler. Had 
it been made immediately after the rain, probably no bugs would 
have crossed the barrier. No further application of oil was made. 
The field was inspected July 6. Only a trace of rain had fallen in 
the meantime, and the barrier had retained the odor of the oil, and 
consequently retained its effectiveness throughout the remaining pe- 
riod of the attack. 

The bugs within the inclosure were so few in number that no ma- 
terial damage was done to the corn, and consequently the stalks had 
made a nearly normal growth and presented a striking contrast to 
the corn outside of the inclosure, which lay withered on the ground. 
No postholes had been dug, so that the insects encountered the bar- 
rier, passed around it, and then straight on into the corn beyond. A 
few, however, turned into the corn back of, and protected in part by, 
the inclosed patch. But as they did not damage it much, it grew 
and appeared nearly as vigorous as the corn within the barrier. By 
July 28 the chinch bugs had scattered, but they had left a trail of 
destruction in their path, all the corn being killed except the small 
patch protected by the oil-straw barrier and the corn immediately 
back of it and an occasional stalk here and there which had escaped 
serious injury. (See PI. V, fig. 1.) 

A harrier inclosing a field versus a harrier along one side only. — 
Barriers are usually erected only between the field from which the 



52 THE WHITE-FUNGUS DISEASE IN KANSAS. 

bugs are about to migrate and the field to be protected. Such bar- 
riers are of value in preventing the injury caused by the massing of 
the bugs in the proximal side of the field into which the bugs are 
endeavoring to migrate, and by permitting destruction to a vast 
number of the invading host, but it should be remembered that when 
a field of grain that is infested with chinch bugs is harvested the 
bugs leave in all directions. 

If the barrier is erected along one side of the field only, the bugs 
which escape from the other sides of the field manage to live on 
grasses and other vegetation, which usually can be readilj' found, 
until they get their wings, when they take wing and finally get into 
the corn. They not only injure it, but raise another brood, the adults 
of which pass the winter and come out in the spring to continue their 
ravages. Just before harvest practically all the chinch bugs in any 
community will be found in the grain fields, and if each one of the 
grain fields in the community were surrounded by an effective bar- 
rier such a large percentage of the bugs could be destroyed that the 
community would be rid of bugs in injurious numbers. If this could 
be done throughout the entire infested area there is little doubt but 
that the bugs could be successfully controlled and thousands of dol- 
lars' worth of damage prevented. However, a barrier along one side 
of a field is worth while and is to be recommended when for any 
reason it is not possible to erect it on all sides of the field. 

Spraying. — It may happen that because of delay in getting an 
effective barrier up, the bugs get into the cornfield and mass them- 
selves on the first rows. When this occurs the spray pump should be 
brought into use, and the bugs killed with kerosene emulsion or else 
with crude oil. 

Kerosene emulsion. — The emulsion is made as follows: Dissolve 1 
pound of laundry soap in 1 gallon of boiling rain water, then while 
hot add 2 gallons of kerosene, or coal oil, and stir vigorously with a 
stick for 10 minutes. The solution will soon take on a creamy 
appearance, but the stirring should be kept up for the full time. 
After the stirring is complete, from 27 to 47 gallons of rain water 
may be added according to the strength of the solution desired. By 
adding 47 gallons a 4 per cent solution is obtained, and Prof. Forbes 
and others have found this solution strong enough to kill most of the 
bugs and not injure the corn ; but in our experiments this season we 
found that a 4 per cent solution did not kill the bugs to our satisfac- 
tion, and that the stronger solution, made by adding only 27 gallons 
of water, killed the bugs almost instantly and did not injure the com 
to any extent when care was taken not to let the spray run down the 
inner circle of leaves at the crown. The important result to be 
obtained is the destruction of the bugs. As to whether the few rows of 
corn sprayed are injured or not, that is a minor consideration. If the 
bugs can be killed by the weaker solution and the corn saved, well 



Bui. 107, Bureau of Entomology, U, S. Dept. of Agriculture. 



Plate V. 




Fig. 1.— Patch of Corn Protected by the Oiled-straw Barrier, and Showing 
THE Destruction of the Corn Outside of the Barrier. (Original.) 




Fig. 2.— Cornfield Showing Corn that was Treated with Crude Oil. The Large 
Stalks in the Lower Right Foreground are in the Row Treated. (Original.) 



REMEDIAL MEASURES AND CONCLUSIONS. 53 

and good, but if the farmer finds that the bugs on the stalks sprayed 
are alive when examined an hour after being sprayed, he should use 
a stronger solution even if it does injure the corn. 

Crude oil. — During the summer campaign an experiment was per- 
formed in Mr. Metcalf's field at Cherryvale, in which crude oil was 
applied directly to the cornstalks when they were badly infested 
with bugs. It was at first supposed that the oil might kill the corn ; 
but it was found that, when applied to the lower portion of the stalks 
and the lower leaves, little or no harm resulted. 

A field of corn lying north of a wheat field was exposed to a mi- 
gration of chinch bugs. No barrier was used and consequently the 
bugs migrated into the corn. It was noticed that the great majority 
of the bugs were located on the stalks and lower leaves. A badly 
infested row was used for experiment and a checkrow, as yet unin- 
fested, was treated in the same way. A bucket of crude oil was taken 
into the field and the oil dashed on the corn and the bugs with a 
bunch of coarse weeds gathered along the roadside. At the first 
stroke many of the bugs dropped to the ground, and the weeds were 
used to dash oil on them. Each hill in the row was liberally treated 
with oil and also the ground about the hill wherever the bugs were 
seen. The bugs were killed instantly and the oil protected the stalks 
from further attack. The two treated rows were watched for injury 
to the corn due to the oil. A personal inspection a month later 
showed no harm done, and a letter from the owner in the autumn 
declared that the rows matured corn in normal manner. The only 
precaution taken in applying the oil was to prevent the oil from get- 
ting into the crown of the young leaves. This method has not been 
tested thoroughly enough to warrant us in giving it our unqualified 
reconmiendation, but so far it has proved very destructive to the 
bugs and has not resulted in any material injury to the corn. 

The use of sprays or crude oil should not take the place of barriers, 
but should be used as a supplementary measure only. (See PI. V,fig. 2.) 

The expense of making this campaign is very slight compared with 
the loss which the chinch bugs will occasion if not molested. The 
reasons mostly given by the farmers for not taking up this fight 
against the bugs is that they do not have time to bother with it. But 
if it is profitable to employ help to raise a crop it would seem that it 
ought to be profitable to put forth some little effort to save it after 
it is raised. 

How to secure concerted action. — This whole subject needs to be 
agitated among the farmers. Township meetings should be called, 
the question discussed, and an organization formed for concerted 
action. At the first meeting called perhaps only a small number of 
farmers, the most progressive, will attend. With the organization 
formed, the agitation should be taken up by everyone interested. A 
time should be set for burning in the fall and efforts made to get 



54 THE WHITE-FUNGUS DISEASE IN KANSAS. 

everyone to burn at that time. In the matter of summer treatment, 
the coal tar or crude oil could be ordered for a whole township at one 
time, resulting in a saving. Active preparation for the fight made 
by a large number before the time for the fight to begin will have a 
wholesome effect upon those who are lukewarm in their attitude 
toward it. 

SUMMARY. 

1. Organize by townships or school districts and counties. 

2. Set a time for burning in the fall. 

3. It it is not practicable to burn off all lands where there are weeds 
and rubbish, burn at least all lands where there are tufts of grass, 
and especially if they are in close proximity to cornfields. 

4. Before wheat harvest secure a good spray pmnp and at least a 
barrel of coal tar or No. 18 residuum asphaltum for every 80 rods of 
barrier to be erected about wheat fields, or two barrels of crude oil 
for the same amount of barrier. 

5. If the weather is dry at harvest time, erect a dust barrier around 
the infested field. Plow deep so as to cover completely all the stubble 
and trash, harrow and drag, then throw out a furrow near to the 
outside border, and start the log as soon as the bugs begin to migrate. 

6. If rain should come, fix up a tar or crude oil barrier around the 
infested field. 

7. Spray bugs that escape to the corn with kerosene emulsion or 
apply crude oil. 

8. Keep up the fight as long as the bugs keep coming from the field. 

Bibliography. 

Note. — The attention of those who are specially interested in the subject of insect dis- 
eases is called to Dr. S. A. Forbes's excellent bibliographies : Economic Bibliography of 
the Chinch Bug, published as an appendix to the Sixteenth Report of the State Entomol- 
ogist of Illinois, and as an Analytical List of American Articles (on Diseases of Insects) 
Consulted, 1824-1894, published in the Nineteenth Report of the State Entomologist of 
Illinois, 1896. 

1. Shimee, Henky. — Notes on Micropus (Lygceiis) leucopterus Say ("The 

chinch bug"), with an account of the great epidemic disease of 1865 
among insects. (Proc. Acad. Nat. Sci. Phila., May, 1867, v. 19, pp. 75-80; 
and Trans. Northern 111. Hort. Soc, 1867-68, pp. 97-101.) 

2. Shimee, Henky. — Additional notes on the chinch bug. (Proc. Acad. Nat. 

Sci. Phila., 1867, v. 19, p. 234.) 

3. Shimee, Heney. — Nature's method of controlling insects. (Trans. Nor. 111. 

Hort. Soc. 1867-68, p. 96.) 

4. Walsh and Riley. — The chinch bug. {Micropus leucoptervs, Say.) (Amer. 

Ent, May and June, 1869, v. 1. p. 177.) 

5. Shimee, Henky. — Entomological notes. (Trans. 111. State Hort. Soc, 1869, 

V. 3, n. s., pp. 275-281.) 

6. Riley, C. V.— The chmch bug. (Second Ann. Rept. State Ent. Mo., pp. 

24-25, 1870.) 

7. Le Baeon, Wm.— The chinch bug. (Third Rept. State Ent. 111., 1871, pp. 

142-156. Also Fifth Ajin. Rept. Board of Trustees 111. Industrial Univ., 
1871-72, pp. 193-200.) 



BIBLIOGRAPHY. 55 

8. Thomas, Cyrus.— The chinch bug. (Bui. 5, U. S. Ent. Comm., 1879.) 

9. FoEBES, S. A.— The chinch bug in 1882. Field notes. (Illinois crop reports. 

Consolidation of reports returned to the Department of Agriculture Aug. 
1, 1882. Circ. 92, p. 77 ; Western Rural, 1882, Farmers' Review, Oct. 19, 
1882.) 

10. Forbes, S. A. — Bacterium a parasite of the chinch bug. (Amer. Nat., Oct., 

1882, V. 16, p. 224.) 

11. PoPENOE, E. A. — The chinch bug and the season. (Prairie Farmer, Nov. 

25, 1882.) 

12. Forbes, S. A. — Another chinch bug parasite. (Prairie Farmer, Dec. 9, 1SS2.) 

13. Forbes, S. A.— Studies on the chinch bug. 1. (Twelfth Rept. State Ent. 111., 

1882, pp. 32-63. Brief summary of discussion in Bui. 111. State Lab. Nat. 
Hist., V. 2, p. 258.) 

14. FoBBES, S. A. — Lecture on insects affecting com, pp. 17-20. (Read before 

a Farmers' Institute at the State Indus. Univ., Champaign, 111., Jan. 29, 

1883, and issued in pamphlet form the same year. Review in Advanced 
Farmer, July, 1883.) 

15. BuRRiLL, T. J. — New species of micrococcus (bacteria). (Amer. Nat., 

March, 1883, v. 17, p. 319.) 

16. Forbes, S. A. — Memoranda with regard to the contagious diseases of insects 

and the possibility of using the virus of the same for economic purposes. 
(Can. Ent, Sept., 1883, and Amer. Nat., Nov., 1883, v. 17, p. 1170) 

17. Forbes, S. A. — Entomological notes of the season. (111. Crop Rept. No. 106, 

Dec, 1883, p. 178.) 

18. Packard, A. S. — The chinch bug. (Guide to the study of insects.) 

19. Weed, C. M. — Rise and fall of the chinch bug. (Prairie Farmer, Oct. 31, 

1885.) 

20. Forbes, S. A. — Chinch bugs in Illinois. (Prairie Farmer, July 31, 1886.) 

21. Forbes, S. A. — The chinch bug in Illinois. (Circular from Office State Ent. 

111., Champaign, 111,, Sept. 10, 1886, p. 8.) 

22. Forbes, S. A. — Present conditions and prospects of chinch bugs in Illinois. 

(Bui. Office State Ent. 111. No. 2, 1887; Fifteenth Rept. State Ent. 111.) 

23. Howard, L. O.— The chinch bug. (Bui. 17, o. s., Div. Ent, U. S. Dept Agr., 

p. 48; Rept. U. S. Comm. Agr., 1887, pp. 51-88.) 

24. Bruner, Lawrence. — Report on the season's observations in Nebraska. 

Chinch bug. (Rept. U. S. Comm. Agr., 1887, p. 165.) 

25. Forbes, S. A. — On present state of our knowledge concerning contagious in- 

sect diseases. (Psyche, v, 5, Jan.-Feb., 1888, p. 3.) 

26. Gillette, C. P. — ^A new chinch-bug enemy. (Prairie Farmer, Aug. 11, 1888, 

V. 60, p. 518.) 

27. Gillette, C. P. — Chinch-bug diseases. (Bui. 3, Iowa Agr. Exp. Sta., Nov., 

1888, p. 57.) 

28. Forbes, S. A. — Epidemic diseases of the chinch bug in Illinois. (Ins. Life, 

V. 1, No. 4, Oct., 1888, p. 113.) 

29. Patrick, I. A. — The new chinch-bug enemy. (Prairie Farmer, Aug. 25, 

1888.) 

30. Forbes, S. A.— Chinch bugs. (Prairie Farmer, Oct. 6, 1888,- v. 60. p. 650; 

Farmers' Review, Oct 10, 1888, v. 19, p. 642.) 

31. Forbes, S. A. — Chinch-bug diseases. (Farmers' Review, Oct. 31, 1888, v. 19, 

p. 692.) 

32. Lugger, Otto. — Fungi which kill insects. (Univ. Minn., Coll. of Agr. 

Bui. 4, p. 37; Abstracts in Farmers' Review, Nov. 14, 1888, p. 721.) 

33. Lugger, Otto. — Notes on the chinch bug in Minnesota. (Ins. Life, v. 1, No. 4, 

Oct., 1888, p. 113.) 



56 THE WHITE-FUNGUS DISEASE IN KANSAS. 

34. Forbes, S. A. — Notes on chinch-bug diseases. (Psyche, v. 5, Sept.-Oct., 1888, 

p. 110.) 

35. Snow, F. H. — The chinch-bug, BUssus leucopterm. Say. (Sixth Bien. 

Rept. Kans. State Board Agr., 1887-88, pp. 205, 208; Proc. 18th Annual 
Meeting Kans. State Bd. Agr., p. 78.) 

36. Forbes, S. A. — Studies on chinch bug, II. (Sixteenth Rept. State. Ent. 111. 

1887-88, pp. 45-59.) 

37. Snow, F. H. — Experiments for the artificial dissemination of a contagious 

disease among chinch bugs. (Proc. 19th Meeting State Bd. Agr., pp. 142- 
144; Trans. Kans. Acad. Sci., v. 12, pp. 34-37.) 

38. Webster, F. M.— The chinch bug. (Bui. No. 22, old series, Div. Ent., U. S. 

Dept. Agr., 1890, pp. 60-63.) 

39. Snow, F. H. — Chinch bugs. Experiments in 1890 for their destruction by the 

artificial introduction of contagious diseases. (Seventh Bien. Rept. 
Kans. Bd. Agr., 1888-90, pp. 14.S-188.) (Twenty-first Ann. Rept. Ent. 
Soc. Ont, 1890, pp. 93-97.) 

40. Riley, C. V. — The chinch-bug Entomopthora. (Ins. Life, v. 2, No. 5, Nov., 

1889, p. 126.) 

41. Forbes, S. A. — The chinch-bug probabilities. (Belleville [Illinois] Advo- 

cate, Mar. 15, 1889.) 

42. Riley, C. V.— The work of field agents. (Rept. U. S. Sec. Agr., pp. 339-360.) 

43. Forbes, S. A. — Economic bibliography of the chinch bug. (Appendix to Six- 

teenth Rept. State Ent., 111., 1890, pp. 1-122.) 

44. Osborn, Herbert. — Entomology. (The Orange Judd Farmer, Mar. 8, 1890, 

p. 158.) 

45. Osborn, Herbert. — On the use of contagious diseases in contending with 

injurious insects. (Ins. Life, v. 3, No. 4, Nov., 1890, pp. 141-145.) 

46. Snow, F. H. — Experiments for the destruction of chinch bugs in the field 

by the artificial introduction of contagious diseases. (Ins. Life, v. 3, 
No. 6, March, 1891, pp. 279-285.) 

47. Snow, F. H. — The chinch-bug disease and other notes. (Ins, Life, v. 5, 

Nos. 1 and 2, Oct., 1891, pp. 69-72.) 

48. Osborn, Herbert. — Fungus infection of chinch bugs. (The Orange Judd 

Farmer, Aug. 8, 1891, p. 85.) 

49. Osborn, Herbert. — The chinch-bug cholera, etc. (The Orange Judd Farmer, 

Oct. 17, 1891. p. 245.) 

50. Cook, A. J. — On carrying chinch-bug disease over winter. (Ins. Life, 

V. 3, No. 6, March, 1891, p. 285.) 

51. Fletcher, James. — Chinch-bug disease. (Ins. Life, v. 3, No. 6, March, 

1891. p. 285.) 

52. Snow, F. H. — Destruction of chinch bugs. (Scient. Amer., May, 1891, p. 

311.) 

53. Forbes, S. A.— General record for 1889 and 1890. ( Seventeenth Rept. State 

Ent. 111., p. 9.) 

54. Forbes, S. A. — Notes on the diseases of the chinch bug. ( Seventeenth Rept. 

State Ent. 111., p. 74.) 

55. Forbes, S. A. — On the bacterial insect disease. (North Amer. Practitioner, 

1891, p. 401; Amer. Monthly Micro. Journ., 1891, p. 246.) 

56. PoPENOE, E. A. — The chinch-bug disease again. (Manhattan Nationalist, 

Feb. 13, 1891.) 

57. Riley, C. V. — The outlook for applied entomology. (Ins. Life, v. 3. No. 5, 

Jan., 1891, p. 181.) 

58. Riley, C. V. — A discouraging fact in Prof. Snow's experiments. (Ins. 

Life, V. 3, No. 6, March, 1891. p. 279.) 



BIBLIOGKAPHY. 57 

59. Riley, C. V. — Microorganisms as insecticides. (Scient. Amer. Supp., Oct. 

31, 1891, V. 32, p. 13206.) 

60. Webstkr, F. M. — Means suggested for the outdoor continuance of tlie Ento- 

mopttiora from year to year. (Ins. Life, v. 3, No. 6, Marcli, 1891, p. 285.) 

61. Snow, F. H. — Tlie cliinch-bug disease and other notes, (Ins. Life, v. 4, 

Oct., 1891, pp. 69-72.) 

62. Snow, F. H. — Experiments for the destruction of chinch bugs by infection. 

(Psyche, v. 6, No. 191. March, 1892, pp. 225-233.) 

63. Forbes, S. A. — Bacteria normal to the digestive organs of Hemiptera. 

(Bui. III. State Lab. Nat. Hist, v. 4, pp. 1-7.) 

64. FOKBES, S. A.— The chinch bug in Illinois, 1891, 1892. (Bui. 111. Agr. Exp. 

Sta., No. 19, 1892, p. 48.) 

65. Forbes, S. A. — The work of the year on contagious diseases of insects. (Ins. 

Life, V. 5, No. 1. Sept. 1892, p. 68.) 

66. Snow, F. H. — Contagious diseases of the chinch bug. (First Ann. Kept. 

Dir. Kans. Univ. Exp. Sta., 1891.) 

67. Snow, F. H. — Contagious diseases of the chinch bug. (Second Ann. Rept. 

Dir. Kans. Univ. Exp. Sta., 1892.) 

68. Webster, F. M. — Insect foes of American cereals, with measures for their 

prevention or destruction. (Ins. Life, v. 6, No, 2, Dec., 1893. p. 146; 
Bui. Ohio Agr. Exp. Sta., No. 51, p. 130.) 

69. Snow, F. H. — Contagious diseases of the chinch bug. (Third Ann. Rept. 

Kans. Univ. Exp. Sta., 1893.) 

70. Forbes, S. A.— General record for 1891-1892. (Enghteenth Rept. State Eut. 

111., p. 10.) 

71. Beuner, Lawrence, and Barber, H. G. — Experiments with infectious dis- 

eases for combating the chinch bug. (Bui. Neb. Agr. Exp. Sta., May, 
1894, No. 34, pp. 143-161.) 

72. Snow, F. H. — Work in economic entomology in the University of Kansas 

for the season of 1894. (Ins. Life, v. 7, Oct., 1894, pp. 140-144.) 

73. Bbuner, Lawrence. — Reports on injurious insects in Nebraska and adjoin- 

ing districts. (Bui. 32, Div. Ent., U. S. Dept. Agr., 1894, pp. 9-21.) 

74. Forbes, S. A.— -The chinch bug in Illinois, 1894. (Press Bui. 16. June 9, 

1894, 111. Agr. Exp. Sta.) 

75. Forbes, S. A.— Chinch-bug experiments. (Special Bui. HI. Agr. Exp, Sta,, 

June 30, 1894.) 

76. Forbes, S. A. — How to fight chinch bugs. (Prairie Farmer, Aug. 4, 1894, 

V. 66, p. 2.) 

77. Forbes. S. A — The chinch bug in 1894. Contagious disease experiments. 

(Bui. State Ent, 111., No. 5.) 

78. Webster, F, M, — Vegetal parasitism among insects, (Journ. Columbus 

Hort, Soc, April, 1894,) 

79. Lugger, Otto.— The chinch bug. (Bui. 87, Minn, Agr. Exp. Sta., Dec, 1894, 

pp. 153-782.) 

80. Forbes, S. A, — Recent progress in horticultural entomology, (Trans, 111. 

State Hort. Soc, 1895, pp. 137-148.) 

81. OsBORN, Herbert, — Observations of insects, season of 1894, (Bui. 27, Iowa 

Agr. Exp. Sta., 1895, pp. 135-149.) 

82. Lugger, Otto. — Insects injurious in 1895. (Bui. 43, Minn. Agr. Exp. Sta., 

Jan., 1896, pp. 99-251.) 

83. Pettit, R. H. — Studies in artificial cultures of entomogenous fungi. (Bui. 

97, Cornell Univ. Agr. Exp. Sta., July, 1895, pp. 339-.37S.) 

84. Forbes, S. A. — Experiments with the muscardine disease of the chinch bug, 

etc (Bui. 38, 111. Agr. Exp. Sta., March, 1895, pp. 25-86.) 



58 THE WHITE-FUNGUS DISEASE IN KANSAS. 

85. Snow, F. H. — Contagious diseases of the chinch bug. (Fourth Ann. Rep. 

Dir. Kans. Univ. Exp. Sta., 1894.) 

86. Snow, F. H. — Contagious diseases of the chinch bug. (Fifth Ann. Rep. 

Dir. Kans. Univ. Exp. Sta.. 1895.) 

87. Snow, F. H. — Contagious diseases of the chinch bug. (Sixth Ann. Hep. 

Dir. Kans. Univ. Exp. Sta., 1896.) 

88. Stedman, J. M. — Chinch-bug infection. (Cir. of Information, 2, Mo. Agr. 

Exp. Sta., April, 1896, p. 3.) 

89. Forbes, S. A. — On contagious diseases in the chinch bug. (Nineteenth Kept. 

State Ent. 111., 1896, pp. 16-141; Trans. Dept. Agr. State of 111., 1896; 
separate, Springfield, 111., 1896, p. 206.) 

90. Webster, F. M. — Three years' study of an outbreak of the chinch bug in 

Ohio. (Bui. 6, o. s., Div. Ent, U. S. Dept. Agr., 1896, pp. 18-25.) 

91. Forbes, S. A. — On chinch bug, bacterial disease of chinch bug, etc. (Twen- 

tieth Rept. State Ent. 111., 1895-96, pp. 35-105.) 

92. Webster, F. M. — Chinch bug and Hessian fly. (Agr. Rep. Ohio, 1896, pp. 

489-495.) 

93. Webster, F. M. — The chinch bug and other destructive insects. (Bui. 77, 

Ohio Agr. Exp. Sta., Feb., 1897, pp. 32-52.) 

94. Stedman, J. M. — Is chinch-bug infection a failure? (Colman's Rural 

World, March 4, 1897.) 

95. Webster, F. M. — The chinch bug. (Bui. 15, o. s., Div. Ent, U. S. Dept. 

Agr., Nov., 1898, p. 82.) 

96. Webster, F. M.— The chinch bug. (Bui. 106, Ohio Agr. Exp. Sta., April, 

1899, pp. 237-248.) 

97. Irvin, N. a. — How to destroy chinch bugs. (Trans. Miss. Hort. Soc, 1899, 

p. 406.) 

98. Bruner, Lawrence. — Chinch-bug inoculation. (Neb. Farmer, July 19, 

1900.) 

99. Marlatt, C. L. — The principal insects of growing wheat. (Farmers' Bui. 

132, 1901, U. S. Dept. Agr.) 

100. Bruner, Lawrence. — The chinch bug. (Neb. Farmer, 1901, p. 441.) 

101. Washburn, F. L. — Insects notably injurious in 1902. (Bui. 77, Minn. 

Agr. Exp. Sta., Nov., 1902; Seventh Ann. Rept. State Ent. Minn., 1902.) 

102. Webster, F. M. — An eight years' study of chinch-bug outbreaks in Ohio. 

(Proc. 22nd Ann. Meet. Soc. Prom. Agr. Sci., 45-57, 1892.) 

103. Parrott, p. J. — Chinch-bug fungus distribution. (Journal of Agr., July 

10, 1903.) 

104. Stedman, J. M. — Status of chinch-bug disease. (Prairie Farmer, Dec. 22, 

1904.) 

105. Webster, F. M.— The chinch bug. (Bui. 69, Div. Ent, U. S. Dept. Agr., 

1907.) 

106. Webster, F. M.— The chinch bug. (Cir. 113, n. s., Bur. Ent., U. S. Dept. 

Agr., 1909.) 

107. Univ. of Kansas. — (Circulation of directions to farmers for the infection 

of fields with chinch-bug disease, 1910.) 

108. Headlee, T. J. — The present status of the chinch bug. ( Kansas Farmer, 

V. 48, June 11, 1910, p. 145.) 

109. Parker, J. B.— Chinch bug. (Cir. 5, Kans. State Agr. Coll. Exp. Sta., 

1910.) 

110. Thorn, Chas. E. — Fighting the chinch bug. (Press Bui. Ohio Exp. Sta., 

Wooster, Ohio, May 12, 1902.) 

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